Oh yes neutered males still get erections, we refer to it as their big lipstick YUCK! Haven't seen any lipstick on Rambeau yet but the labs . . . different and amazing story. They could have vesectomized your boy but probably not. When he is in a relaxed state, check for blackeyed peas between his back legs. Chances are, the new smells and experience just turned him on. Previous poster was correct the prostate, bulbo urethral gland and seminal vesicles can all produce fluid. Usually this doesn't happen to a dog that has been neutered for a while. If this was a new and exciting experience who knows. I wouldn't worry about it though - boys will be boys
Have your vet double check next time your there.
Melissa and Rambeau (bulbo what???)