I had one that did the same thing. It was pretty old and I could not find a rebuild kit for it so I ended up tossing it and buying a new one.
Does it still climb if you leave it on and disconnect the QD from the keg? If so that will rule out something in the keg carbonating the beer.
If your regulator is new or even reasonably new I would try to contact the manufacturer if you can't figure out what is going on with it. If it is new I would not disassemble it before contacting them or where you purchased it.