Rabbit Hopping Stiffly

Hi everyone,

I have a male rabbit, neutered, unknown breed (maybe flemish giant mix... he's pretty big, rescued as a meat rabbit) about 2 1/2 years old.
Today was the first nice day of spring, so we took him out to a safely enclosed area in our backyard for him to play. He loved it and spent most of the time out there running and binkying. After about 2 hours I brought him in, since I didn't want to suddenly strain him with all the exercise and I had to leave for an appointment soon anyway. I cleaned off his feet (which he didn't like much) and let him be.
I left and came back about three hours later to give him dinner and found him hopping really stiffly. His hind end was lifted really high up, and he didn't put his back feet flat -always raised up like he was keeping weight off his heels.
He otherwise seems fine - he ate dinner happily, had some hay - but doesn't seem to want to move much. No teeth grinding or hunching while laying down.
Is it possible he's strained a muscle and feels stiff or possibly injured his hocks (he has some light sores from being on less-than-ideal carpet, but never acted this off) or could this be something more serious?

Thanks for all the help, it's greatly appreciated!

I give mine a joint supplement. Might just be stiff from the extra activity. Keep a close eye on him and maybe visit your Vet.

Update - he seems more or less the same. Still pretty stiff, not willing to move too much. I've seen his recent poops and they're healthy as ever. He's eating maybe a bit less, but he's always working on his pellets/lettuce/hay slowly throughout the day. He's as passionate about blueberries as ever! I've carefully picked him up a few times to feel for any bumps/hot spots/tenderness but haven't found anything significant. I may take him to the vet tomorrow, maybe wait until Tuesday (As Sunday and Monday it'll likely be closed) - I feel like there hasn't been any changes severe enough to merit a vet visit just yet but I will take him if he doesn't show improvement soon.

If he's limping that severely, I would take him in to the vet. As long as he's eating and pooping, it's not an emergency or anything... but by Tues, it will have been nearly a week - if he's not significantly better by then, I think that's cause for concern. By the way, have you been seeing cecal poops around his area or does he appear to still be able to get down there to eat them? Either way, the answer would probably be useful to the vet, so keep an eye out (also make sure they're not stuck to his butt).