L.S.
Gosh my son does the same thing. He also does this silly stance where he "re-arranges" himself. I think it's a boy thing. How is he when he wears jogging pants or sweats. If it the same thing then you are right it's a Tic he's not really "re-arranging". I just tell my son to please go in the bathroom if he needs adjust himself and tell him that's is just proper b/c those are his privates parts. Heck he maybe even going thru puberty. Ask your husband to help out in that case.
Hope this helps.