Last night when my dh came into the room and I was half asleep I jumped (like you do) then thought I was someone else and asked why I was in this bed and where's mummy (ie me).
If dh had told me about it this morning I wouldn't be worried but as it is actually me remembering it very clearly, including the terrifying feeling of not knowing who I was, I am rather worried that something's wrong.
The only other time something a bit like this happened was 5 years ago when I was extremely sleep deprived with a new born and I woke in the night not able to remember dh's name. I didn't worry about that in the same way though as I knew the tiredness explained it. I am tired now but not hugely.
Any advice/ideas please?