one lifter bleeds down. Any thoughts

I had the same problem with the Buick 350 in my truck. I bought a Comp cam/lifter kit and have never been happy with the lifters. I had a couple which would bleed down in 1-2 seconds after the engine stopped, and they were noisy on startup. Replaced with TRW lifters, and much better. Not impressed with whatever brand of lifters Comp sends with their cams.