Good point! I don't remember the name of the town/ area, but I do remember Dex saying last episode that it was a lengthy drive away (like over an hour, I think?). So, not Portland.
Overall I enjoyed the episode (and the season in general) due to the characters/ actors, fun music choices, etc., but I had the same complaints this episode as I posted last episode, in that they're moving through story lines so quickly that they're already repetitive. I mean, we've only had eighteen episodes and the "big" character cliffhangers they leave us with are Miles questioning whether he's cut out to be a cop for the second time, and Grey being reluctantly pulled into some kind of illegal activity for at least the third time! (Guy really needs a hug, by the way.)
Of course the return of Dex and Ansel's mom is something new, but they ruined it a bit by making it super obvious it was coming. The very first scene with Ansel being secretive on the phone, I knew it was the mother.