You have a right to raise your concerns, if you spot something that might cause problems in the future. One thing about Wetsuit is this, if there are concerns raised, he or she will address those concerns. Wetsuit will either explain it in detail or he will improve the system.
I've just heard from wetsuit and I've asked him to have a look at this. My personal view and understanding is that sort of manipulation wouldn't work because there's a nonce on the client side. The argument that the server seed could be changed is negated by the fact you could easily implement a script that checked that before and after each roll. I'm sure there are enough sceptics out that have tried to catch sites out and have failed because they don't actually cheat. It really wouldn't be worth it, the site's reputation is worth far more than any individual bet.