Are these early signs of Alzheimer’s or stress?

My mom has been forgetful lately. She’s been really busy at work because a lot of stuff has been going on. Sometimes she’ll ask me about school but I’ll have to tell her that I already told her how my day went but sometimes I think that she wasn’t paying attention Bc she was thinking about work. Yesterday she put a plate of cookies away and forgot what was on the plate but remembered right away that she put cookies away but to be fair it was pretty busy Bc she was helping me get ready for a party. She doesn’t have any memory problems with work and never forgets any important things especially doctor’s appointments. I’m just a little concerned. She has had depression before due to stress. Today I was home from work so she wanted me to feed our pet but she forgot to tell me to feed him before she left. But I later asked if she was in a hurry and she told me she was. Are these early symptoms are just stress related problems due to work?