Welcome to iPhone Forums, idiomar!
Try resetting your iPhone: press and hold Home and Power button at the same time until you see the Apple logo. Then release both, and let your device power up on it's own. This kind of reset won't remove data or change settings, but it can help with the bug you're experiencing.
Another suggestion that might help:
If you updated over the air (in Settings - General - Software update), then connect your iPhone to iTunes and restore it. Make sure there's a most recent backup to restore from before starting the process.
Hope that helps.