Presure in Radiator

Do you believe that radiator can have pressure even it is not hot or unclosed radiator cap?
In the first time i know that it can't happen, but when i experience it well all i can say that what happened. I ask some mechanic about it they said old cars sometimes have these kind of problem the only solution is to remove the cylinder head and go to machine shop to resurface it and change the gasket of the cylinder head. If you know to do it you can do it your self than making high cost for the repair that even you can do it, with the proper tools and knowledge you can fix it by your self.