So a friend of mine brewed a golden ale with oats recently. He put it in the keg without taking any gravity readings, and I personally think he kegged it too early (this may or may not matter, I'll get to that in a second...) as it had a pretty heavy mouthfeel initially. After kegging and force carbonating, it seemed like it had a ton of foam from the kegerator that it was in (his then roommates). We took it to his newly purchased home for moving day to keep the troops hydrated. Still lots of foam there, in a trash can with ice, different QD and lines and faucet.
There was about 2 gallons or so left over after moving day so we brought it to my garage and put it in my kegerator. I have 10' 3/8" thick wall beer lines with Perlick faucets. I was still seeing lots and lots of foam, so I cracked the fridge door and sure enough, it was foaming IN THE LINE as it left the QD, all the way up to the faucet. I was getting about 1/4 glass of beer and 3/4 glass of foam. After checking all the connections and talking to my LHBS, the suggested I check/replace the o-rings on the beer out post and diptube, which I did. Still seemed to have a lot of foam. I let it set for 2 weeks or so, not knowing what to make of it. I checked it again today as I was going to tear into his keg and see if I could fix it, but I got a perfect pour, the first half glass with lots of yeast. Dumped that out after sampling and poured another pint and it came out clear and without any real foam. I checked carbonation and it was spot on, and it foamed if I let the beer fall 12" or so into the glass. Head retention was good. It also tasted a fair bit dryer than I remember it tasting before, without the thick mouthfeel.
Is it possible that since he kegged it before fermentation was complete, this was causing the foaming in the line before it even reached the faucet? And after 2 weeks at 40* (very slow fermentation, I realize, if any at all) it finished out and there is no longer much yeast in suspension? I'm just trying to wrap my head around why this awful foaming problem would just stop on its own in the kegerator without external influence...
Thanks and cheers!