I have done some searching on the forums and cant really find any info, but someone was talking about getting their beer infected from the gas lines. He was purging his carboy after taking a sample and it hosed the ale. I havent had this problem, but I recently racked my Pliny clone for dry hopping and decided to carb at the same time. I usually carb in the fridge, so I dont think about bacteria in the lines, and I have never replaced or cleaned my gas lines. I have cut off a connector to put a pin lock on, but thats it. Is it possible for your lines to infect your beer when carbing at room temp?

Edit: I have never had any backpressure put beer in my lines either.

You should not have a problem providing you properly sanitized your gas lines before using them for the very first time. After that they are in a sealed environment open to only CO2 which does not allow much to grow. Temperatures should have no real effect on this issue as I have carbed in both fridge temps and room temps with no infection issues.

You should be good. Gas lines are not the first place I would look to find an infection.

His carboy was opened up, and he put something in there to draw out the sample... it could just as easily have been his thief or just stuff drifting in that f'ed his brew instead of his CO2 line...

i cant see the gas line being an infection source but if you are really that worried why not just replace the gas line? for the 2 bucks it'l cost it might be worth it just to keep you feeling more relaxed.