gaining time

I've heard of people losing time for brief periods, looking at their watches and wondering where the last hour or two vanished, no memory of what they were doing.
Ever heard of anyone gaining time?
Happened to me today; looked at my watch, and had the extraordinary feeling that somehow, I've moved back in time. It should have been at least an hour and a half later than it was.
I'm scared. My mind either misinterpreted everything that had happened before that... or created incidents that never really happened.