Early dementia symptom? Mom keeps saying she's seen things before that she hasn't.

It is very possible that your dad was "covering" for your mom with her memory loss.
There are statistics that indicate that a high % of seniors taking care of their spouse with dementia often are diagnosed with dementia themselves. Now I do not know if just due to their age they might have been diagnosed with dementia anyway. Or is it isolation that often comes with caregiving.
It is possible that what you are describing is dementia.
It can take a person with dementia often 45 to 60 seconds to process what is said, heard or seen. If this is the case seeing a car on the side of the road, a room full of people if you "see" these things and it takes a while to process the image the brain just might be overlapping the image that was processed and what she is seeing in the moment so it might seem like a memory. Sort of like Deja Vu.
It could also be a UTI that is causing symptoms that you would never think to associate with a UTI. (There are test strips you can get OTC so that you can try to do a quick test before you even call for an appointment)

SadDaughter4, have your Mom tested for an Urinary Tract Infection [UTI] as such an infection can cause all sorts of weird problems when people are older. Her primary doctor, or even Urgent Care, and run the test which is pretty simple. UTI's are treated with antibiotics.

My mom does the same thing. She has not been formally dxed with dementia, but I think simply the burden of 92 years of life and trying to remember what, who, when...she's exhausted.

All she ever wants to talk about is her ONE living friend, b/c that's always who she saw last and she can remember a few days back pretty well.

The 90 years leading up to where she is now is pretty jumbled. We all know it and just don't harass her if she makes a mistake in 'remembering'.

Thank you - I think you're exactly right that we have to trust what we are seeing. It's so easy, sometimes, to rationalize and explain things away. I've contacted her doctor now and hope we can get her an evaluation soon.

https://health.clevelandclinic.org/deja-vu-what-it-is-and-when-it-may-be-cause-for-concern/

Since you are already dealing with your father's dementia I'm sure you know how to go about asking for an evaluation, either with a simple MMSE or a more comprehensive tests.

my Mom lived in a different state than me. I should have realized when she started telling me odd things, that she was hallucinating. That she was cognitively declining and needed more care. So , yes the cat sitting on a pole was not her eyesight. .. the people outside her window, not there….the stolen objects(that I found)… The monkey in the cactus should have sent me a huge red flag, but , you know…, yeah she seamed ok…. When I moved her by me, the hallucinations progressed. Needed prescription interventions. Trust what your seeing… she is hallucinating…