Well, I’m not a doctor…
However, if your scrotum is shrinking up to the point of pain, then, yes, something is probably seriously wrong. But, if it is just shrinking a little bit and shriveling up, like a rumbled blanket, with no pain, or discomfort, then it is probably normal.
I personally have this happen a lot to me, ever since puberty (when my balls descended). If I have to go very badly, and can’t, they pull up against my body, regardless of temperature. But that only happens if I have been holding it (urine or otherwise), for an extended period of time. This usually happens if I am “in the zone” working, and don’t realize to I stand up hours later.
I know it is not normal for some men, and for others it is. It’s possible the effect was smaller before surgery, or you never noticed. It is also possible that something is wrong.
If you have the means to see a doctor, I would do so, no matter what. You know your body best, and if it is worrying you, then you should get it checked out. As others have said above, it would be better to know, rather then find out the hard way.