I had a TIA but I remember it. It started with a very bad headache. I was taking two friends out for lunch on New Year's Day a few years ago, and I was telling them about the headache. They started to ask me questions, and all I could do was laugh and mumble. I was trying to answer but I just couldn't. It was horribly scary. It went away after about an hour, but I still worry about it.
I think it was stress-induced, it hasn't happened again... but I'd be very concerned if I couldn't remember it and it lasted so long.