The other thing I can think of is simply just the aging of the beer. The first keg that was fermented at 68 ,my wife wouldnt even drink it. She handed it back to me. Now after the second keg was tapped she is trying to drink the whole damn keg by herself because she likes it. The second keg was put into service about two months later. Maybe it is simply due to aging, and cold conditioning the beer longer. Dunno, and I wish I had some of the first keg left to do a side by side comparison
That might do it, Grant. As as Fred mentioned, suspended yeast can impart a kind of bitterness. CL-50 isn't always a fast flocculator, so the age difference may very well be what did it.