It’s never wrong to get a medical opinion, best would be from a cognitive/behavioral neurologist, if one is available near you.
What kinds of things is she forgetting? Do reminders help? Is she aware of the lapses? Is there any change in the way she is speaking or in her personality? How old is she, and does she have any medical problems or take medications that can affect cognition? These are some of the things they will ask, to help steer you and her toward reassurance and/or further testing.
There are probably message boards designed for this specific question, instead of a sub forum on a strength training site, but you asked it here, so...