OK, So I know this thread will either go down in history as me embarassing myself and missing something obvious, or people simply won't believe me.
Since upgrading to iOS 7, and not before, I've facetimed my girlfriend a couple of times the night before last, and once this morning. She didn't answer (no jokes please

).
Anyway, a few minutes later a mate texts me asking why I've just tried to facetime him. I said I hadn't, suggested (as a joke mainly) it was iOS7 and he replied saying it had happened a couple of times the other night too.
It seems almost replicatable. If you use contacts, its fine. If you go into messages, select my gf, scroll to the top of the messages and press Contact > Facetime, it comes up with the video screen with the correct name at the top, but by all accounts - it calls someone else.
My call history shows I facetimed the girlfriend. My mate's call history insists I've facetimed him. Girlfriend confirms she hasn't had any missed facetime calls.
I've checked the contacts, all seems good.
Am I going mad?