Ok, I restarted the iPhone, after boot I started mail and then Reeder. Both crashed into black and home screen, and this is what the console told me:
Jun 16 14:12:08 myPhone2 UserEventAgent[13] <Notice>: jetsam: kernel termination snapshot being created
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (UIKitApplication:com.apple.mobilephone[0xb6ba][106]) <Notice>: (UIKitApplication:com.apple.mobilephone[0xb6ba]) Exited: Killed: 9
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (com.apple.TextInput.kbd[51]) <Notice>: (com.apple.TextInput.kbd) Exited: Killed: 9
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (com.apple.tccd[98]) <Notice>: (com.apple.tccd) Exited: Killed: 9
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (com.apple.librariand[107]) <Notice>: (com.apple.librariand) Exited: Killed: 9
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (UIKitApplication:ch.reeder[0x103][125]) <Notice>: (UIKitApplication:ch.reeder[0x103]) Exited: Killed: 9
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (UIKitApplication:com.apple.mobilemail[0xb940][105]) <Notice>: (UIKitApplication:com.apple.mobilemail[0xb940]) Exited: Killed: 9
Jun 16 14:12:09 myPhone2 com.apple.launchd[1] (UIKitApplication:ch.reeder[0x103]) <Error>: (UIKitApplication:ch.reeder[0x103]) Bug: 10B329: launchd + 66777 [10FF8D45-0402-39D1-B479-CDDF29E6B50E]: 0x16
Jun 16 14:12:09 myPhone2 backboardd[26] <Warning>: Application 'UIKitApplication:com.apple.mobilephone[0xb6ba]' exited abnormally with signal 9: Killed: 9
Jun 16 14:12:09 myPhone2 SpringBoard[67] <Warning>: Memory level is not normal. Pending auto-relaunch of 'com.apple.mobilephone' until it is.
Jun 16 14:12:09 myPhone2 backboardd[26] <Warning>: Application 'UIKitApplication:ch.reeder[0x103]' exited abnormally with signal 9: Killed: 9
Jun 16 14:12:09 myPhone2 backboardd[26] <Warning>: Application 'UIKitApplication:com.apple.mobilemail[0xb940]' exited abnormally with signal 9: Killed: 9
Jun 16 14:12:09 myPhone2 SpringBoard[67] <Warning>: Memory level is not normal. Pending auto-relaunch of 'com.apple.mobilemail' until it is.
Jun 16 14:12:17 myPhone2 ReportCrash[135] <Error>: libMobileGestalt copySystemVersionDictionaryValue: Could not lookup ReleaseType from system version dictionary
Jun 16 14:12:17 myPhone2 ReportCrash[135] <Error>: Failed to save memory report to /Library/Logs/CrashReporter/LowMemory-2013-06-16-141217.plist using uid: 0 gid: 0, euid: 0 egid: 0. 100 logs already present.
Jun 16 14:12:17 myPhone2 ReportCrash[135] <Error>: Error: 2 No such file or directory
Jun 16 14:12:21 myPhone2 kernel[0] <Debug>: launchd[136] Builtin profile: container (sandbox)
Jun 16 14:12:21 myPhone2 kernel[0] <Debug>: launchd[136] Container: /private/var/mobile/Applications/8944B769-3F55-4659-867E-1CC0B5B5F2C5 (sandbox)
Jun 16 14:12:23 myPhone2 UserEventAgent[13] <Notice>: jetsam: kernel termination snapshot being created
Jun 16 14:12:23 myPhone2 com.apple.launchd[1] (UIKitApplication:de.avm.FRITZApp[0x1808][136]) <Notice>: (UIKitApplication:de.avm.FRITZApp[0x1808]) Exited: Killed: 9
Jun 16 14:12:23 myPhone2 backboardd[26] <Warning>: Application 'UIKitApplication:de.avm.FRITZApp[0x1808]' exited abnormally with signal 9: Killed: 9
Jun 16 14:12:23 myPhone2 SpringBoard[67] <Warning>: Memory level is not normal. Pending auto-relaunch of 'de.avm.FRITZApp' until it is.
Jun 16 14:12:24 myPhone2 syncdefaultsd[80] <Warning>: received memory warning
Jun 16 14:12:27 myPhone2 ReportCrash[138] <Error>: libMobileGestalt copySystemVersionDictionaryValue: Could not lookup ReleaseType from system version dictionary
Jun 16 14:12:27 myPhone2 ReportCrash[138] <Notice>: Not saving suspended-only Jetsam log because already dumped today.
Jun 16 14:12:28 myPhone2 com.apple.launchd[1] (com.apple.networkd_privileged[137]) <Notice>: (com.apple.networkd_privileged) Idle-exit job was jettisoned. Will bypass throttle interval for next on-demand launch.
Jun 16 14:12:28 myPhone2 com.apple.launchd[1] (com.apple.networkd_privileged[137]) <Notice>: (com.apple.networkd_privileged) Exited: Killed: 9
Jun 16 14:12:28 myPhone2 UserEventAgent[13] <Notice>: jetsam: kernel termination snapshot being created
Well, I did not start "FRITZApp", and I am not sure what "Memory level is not normal" means. I guess my iPhone has damaged RAM?