I could see all the stuff during the visit as the result of an awful, crippling social anxiety, up to and including the lack of thank-yous or offers to pay for anything. ("Is it too early to ask to split the check? What if it is? I'd look like such a fool, oh my god it would be so awkward, what is wrong with me that I can't do this simple thing... wait, she's reading it, do I do it now? But what do I say? She must think I'm such an idiot. Oh no, now what? Is it too late? Did I miss my window? What if she's mad that I'm not offering to pay? Should I say thank you for paying, or will that just make her madder because it'll sound like I assumed she would pay? Augh, better act like it's no big deal either way...") The weird part is the behavior afterward. If it were just social anxiety, they'd know exactly how badly the visit went, and either try to cut their losses by pretending it didn't happen or disappearing on you, or apologize to you with an explanation. What you're describing is just so weird.

I think you should say something. Tell them you've been a little upset since the visit, and why. You deserve an explanation, and they deserve the chance to explain themselves.