Cold shoulder after hookup?

So I met a guy through Grindr and we Snapped each other a lot, for like 2 weeks or so before we finally met and hooked up. I was surprised at first because I'm 45 and he's 20, but said he's really into older guys. I really enjoyed chatting with him via Snapchat and after we finally met up I already knew I wanted to see him again (that's not usually the case!) I sent him a message a few days later, just asking how the weekend was, etc. not a lot of chat, just a basic question and he responded to a couple of chats but he didn't even respond to my last question (small talk) and hasn't snapped me since then. Am I reading too much into this? Trying to figure out if this is a sign that he's just not as into me as I am into him or maybe he's just busy. I've given him space and haven't reached out to him since then. It's been 4 days and I'm wondering if sending another "hello" type of message is cool or should I wait to hear back
from him first? Thanks for any advice - BTW given my age (ha ha) I'm not an expert at interpreting Snapchat etiquette. And - the guy is quite a bit younger so maybe communication means something different to him than me. ??