Lifter noise?

I've got a 360 with a hydraulic roller cam/lifters. It has what sounds to me like a lifter tick. The interesting thing is the sound will eventually fade away. The fading away is NOT related to the engine warming up. Sometime I can make the tick come back if I rev the engine to about 4k. The tick will persist for a bit and eventually fade away as the engine is idling.

Does this sound like a bad lifter or could there be something else going on?

Thanks!