Do you have testes that are about the same size ? Are you a lefty or righty - biggest is on left / right?
My left testicle has a bit of "vascularity" (if I remember the word the doctor used correctly). The tubes aren't knit together as tight as the ones in the right testicle. It doesn't hurt, doesn't effect sperm production, but my left ball is looser than my right. (Hangs lower too, but I "dress to the left" so that might be a factor in the hanging.)
I have one on the right that drops down a bit and seems to be a bit heavier...When I first noticed this I was bit worried but then learnt this is quite common.