It happens from time to time. Check him after he shed's completely to see what they look like then. If they are still dented then I would suggest you bathing him. Make the water about 85-90 degree's (read it with a temp gun, if you have one). Soak him in a sealed tub for about 15 minutes and then they should just peal right off.

That's what I would do if they didn't come off in the shed. Seems to work just fine for me.

70-75% should be enough for him to shed as well. I wouldn't do anything different next time.