Why do men reach out after months?

I was in a situationship with this guy on and off for about 2 years. This past July we officially ended things cause we both were in different places and wanting different things. I got a point where I was dating for a relationship and didn’t want to keep that going with him. We ended on great terms. I get a text from him today saying “sorry to hear about your dog passing.”…idk where he heard about my dog passing and I guess It was a nice thing to say but not necessary after not talking for 7 months. We closed the door for good, why open It. I assume for sex, idk. Has anyone else experienced this?