does it smoke or run rough? I did a compression test on a room temperature motor that had run the day before and it tested the same as warm. I also noticed that if you pull injectors, and then bleed the oil out the open glow plug hole, that the compression from all the oil will read 500+.
I would warm up the engine slightly to get the lube splashed on the cylinder walls and let the rings clean it off while coming up to a moderate temperature. like just let it idle for a minute, even with the valve covers off.
a leak down test wouldn't hurt if you know how to do it. compare it to a good cylinder and see where the air goes.