She may just not be very good at remembering faces, or perhaps her eyesight is a bit weak. I occasionally go out without my glasses and then a couple of days later, someone will say that I ignored them in the street, when actually, I didn’t see them at all.
And I’m useless with faces - I need context to figure out who someone is. I once did a 16 mile sponsored walk over quite strenuous terrain with a woman who clearly knew who I was because she asked after my kids, but I hadn’t a clue who she was. Then I went into the local library, and the librarian I chatted with every week for years asked me if I’d got over the walk yet, because her thighs were still aching.
Please don’t assume it’s personal and take offence. Just be your normal charming self, and be charitable when interpreting her intentions.