Thank you both!
I think - and hope - that he's happy. That's all I want! He is always busy, foraging and running and digging through his sand or soil pits. I tried to helpfully unblock one of his tunnels this week and he immediately went and blocked it back up
silly me! I can't thank everyone enough for the advice and help; he seems like the happiest, most optimistic little hammie I've ever owned and its wonderful to see.