Memristors are ultra cutting edge and mostly theoretical/still being studied in labs. If this person is an engineer in industry it makes sense they have not heard about it.

EE is a huge field. It's hard to keep up with new developments even if you have a broad foundation. That being said, memtransistors and memristors have been theorized and subsequently developed in research for quite some time now. Memrsistors were first theorized in the 50s and then in the 70s were proposed to be a fourth fundamental electrical circuit element alongside resistors, capacitors, and inductors.

I'm surprised - I'm purely a software developer and I've known about memristors for years, probably decades.

Given that the existence of memristors was first predicted by a professor at Berkeley (Leon Chua), yes I am surprised. Surely he had to have heard of them.

Memristors are a pretty niche topic. Until somebody made some, they were an obscure topic in circuit theory. Even now that they exist, they've yet to be commercialized. It makes sense for a practicing EE who may not follow the tech press all that closely to not know about them.

I studied EECS at Berkeley, but almost entirely just CS. I took maybe 1 circuits class. Even I have heard of memristors and Leon Chua.