Thanks for the ideas, I don't think installing the ball valve had anything to do with it as I was able to do it without having to turn it on it side just role it a few feet from the wall. It might have been going on for a while and just noticed it. I never change the line pressure and the unloader vents over the line psi gauge and noticed it when I adjusted the line pressure after changing the valve. No noticeable oil in the line or tank. I will give your ideas a try and if those don't work I will just have to live with it for now as a new compressor is not in my budget.
Sometimes we see what we expect to see, and not what we are looking at! Scott