No surprise, I'm also on the side of "you're definitely not expecting too much".

For the record, I feel very similarly about email. My old T once reached out by email to ask how I was doing (I was traveling for work, and it was extremely stressful) - I sent him a brief reply, and then... nothing.

I tried to explain that it felt like we had seen each other out in the world, he had said, "hi, how are you?" and I said, "great, how are you?" and instead of replying... he just turned his back, ignored me, and walked away. It was hurtful. And, I wasn't expecting a long, involved response either - but why engage me and then not respond at all? Even just saying something like, "Thanks for the update, sounds like you're managing. See you when you get back!"

Bah.

Especially since you guys have already talked about it, and he agreed to reply, of course you should expect him to reply!

Good luck talking to him about it!