Boy, the canted barrel issue seems to be pretty common these days. Really surprised that the manufacturers don't pay more attention to this problem when the barrel is being assembled to the frame. Apparently, this is not something that QC looks for before shipping the gun.
I have been in the market for a 686 Plus for a few months. I looked at 4 PC versions and one Plus model a few weeks ago and 3 of the 5 had canted barrels.
And, yes, you should send the gun back again until they get it straight. That kind of stuff really bugs me as well.
Update: LGS called this afternoon and said he was holding a new 686-Plus, 2.5" barrel in the back room if I wanted to come down and inspect it. Got down there ASAP, took the gun out of the case, and, yes, the barrel was overclocked 1 to 2 degrees. Ribbing on top of the frame was noticeably mis-aligned with the ribs on the barrel. Dealer even agreed that it was off. That now makes 4 out of 6 new Smiths that I have looked at in the past few weeks that had canted barrels. Seems to be the rule now, rather than the exception.