Recent iPhone authenticator issues

I've had this issue for the past two or three days which has really REALLY freaked me out (resembled being hacked once before). It seems that my iPhone authenticator has been randomly coming out of sync with I'm guessing the server that runs the algorithm. I wanted to know what would cause that because it's kind of nerve wracking to be offline more than three days and come back to a screen that says "your information is invalid"