She frequently loses it. Today she called me (she has no land line, so naturally she was calling on her cell). During the call, she said "Oh no, I can't find my cell phone". I said "Mom, you're talking on it right now." "Oh yeah" she said.
Mom is 81 now. I have noticed mental slips like this the last year or so, but they appear to be getting a bit worse. My dad declined mentally in his last 6 months or so, I didn't noticed his mind going before that. Mom I don't know about. She goes to the doctor regularly, and her mind is still lot sharper than my dad's toward the end.