Hey Hobashi,
It sounds like the songs might be having issues downloading. To troubleshoot, try the following:
Signing out of your account in Settings > iTunes & App Store. Once signed out, go ahead and restart your iPhone, then sign back in.
via: iOS: Changing the signed-in iTunes Store Apple ID account
http://support.apple.com/kb/HT1311
and
iPhone, iPad, iPod touch: Turning off and on (restarting) and resetting
http://support.apple.com/kb/HT1430
If you continue to experience the same issues, there might be an interrupted download that is preventing other content from downloading. See the following article to learn how to resume interrupted downloads:
iTunes: How to resume interrupted iTunes Store downloads
http://support.apple.com/kb/HT1725
Welcome to Apple Support Communities!
Regards,
Delgadoh