There are some studies suggesting that type 2 diabetes might be prion-transmitted, which are not destroyed by normal sterilization techniques. So we might be transmitting that (and god knows what else) with routine surgery.
Yes, and that's not mutually exclusive with there being a biochemical risk factor that triggers it or increases susceptibility.
It is certainly a little out there, but if I had to guess at some hidden danger that's ubiquitous in our environment to which we are oblivious, I'd say "prions are more prevalent and dangerous than we think" isn't a bad place to start.