Jason, my old Mirro-Matic's instruction booklet actually advises to immediately run the whole thing under the faucet with cold water to reduce the pressure before removing the weight, so it sounds like you did the right thing. The booklet that came with my recently purchased Presto is much smaller and less informative and I can't remember if it gave the same cool-down advice but that's what I do with it anyway. I like the fact that it's unpainted since the Mirro is looking pretty beat up in 60's avocado these days. I try to keep the new Presto looking nice by wiping it down after washing it so it won't spot. Very hard water where I am so I'm always dealing with spots on everything.
And I'm going to have to start a new thread sometime when I roast a chicken in my 50's rotisserie. The only way to go IMHO as it comes out perfect every time and makes the whole house smell like an expensive deli!