Google Calendar syncing suddenly gone

I've been successfully using a synced Google calendar (with iCal or Calendar, depending on iOS and OSX versions) across all my Macs and my iPhone for a year now. No problems, until today. I didn't change anything, nor install/uninstall anything. I've created several events on my iMac and they won't appear on the iPhone Calendar. Then I entered my Google calendar account with a web browser and checked that the events are successfully stored in the Google server. So, syncing worked fine from the iMac to Google. Then I tried to create a new event on the iPhone, and it was successfully synced to the Google server (I cannot test if the iMac will sync them because I'm not at the office now). But there's no way to sync to the iPhone the events I created on the iMac.

I'm on iOS 6 if that matters, but it worked fine until today.

Are more users getting problems like this recently? Are there known workarounds?

Thanks!!