Mysterious swollen hand after TRSR.

I have an issue with my hand swelling up at night.
This started about two months after a TRSR. I'm making good progess with physical therapy, and when I mentioned this swelling to my hand he dismissed it
The surgeon said it happens sometimes.
Why? This is a little annoying waiting for my hand swelling to go down and start my day.
Anyone have this happen to them?
There is no pain involved. It's just swelling of my right hand.