TMZ is reporting:
Actor -- who plays shapeshifting werewolf in the " " movies -- was arrested in Tempe, Arizona early Monday morning ... this according to the Tempe Police Department.
Gordon was NOT busted for DUI, as reported by local AZ media -- but rather, he was arrested for an active warrant stemming from a drug paraphernalia possession arrest in 2010.
Law enforcement sources tell TMZ ... the 21-year-old actor was a passenger in a vehicle that was stopped for a "routine registration check" in Tempe around 6:12 AM.
During the stop, cops discovered there was an active warrant for Gordon's arrest -- so they took the actor into custody and booked him into a local jail.
TMZ has obtained the police report from Gordon's 2010 arrest ... in which the actor was popped for carrying a glass marijuana pipe and for being in possession of alcohol while he was underage.
According to the report, Gordon's beverage of choice was Four Loko -- a drink that has been banned in several states.
Stephenie is going to be so disappointed... and we all know that's so much worse than angry. Silly boy.