I've only had one of my dogs neutered and he was 30 months when I had it done, so I was a newbe, also. It doesn't sound like there is any cause for concern. The scrotum shouldn't be swollen, but it can remain fairly normal looking for several weeks. I was only able to keep mine quiet for 2-3 days and he had no problems. If it doesn't feel hot or swollen, I think you're ok.
'If you find a way to enjoy the ride, it doesn't really matter where you end up'
5 GSDs at the gate: Katie, Iroc, Red, River, Jake