Ya, my nuts hurt when they begin to shrink as well on they're way back to normal. I read this your post with a smile on my face, cause just the other night as was feeling it while in bed. Not overly painful, but def not fun.
I have had the nuts ache while on, and while coming off, so yeah I would say it is normal for some. It has only happened to me once though. Scared the bejesus out of me at first lol.