Very slow...

Last night I woke up around 5AM to use the restroom and I went to check on my Hayden. I saw him running on his wheel but...he was doing it really really slow? He's usually quite active on his wheel and runs really fast...but last night when I was peeking at him (I know he couldn't hear me and I wasnt very close to his home) he was just going very slow and it looked like he fell off once. Is he ok? Maybe he was just being lazy? I'm not sure if this is normal or not. Other than this he's been acting pertty normal lately, still quilling though. Thank you for your help