That's the way it goes. Sometimes you never know how things are until you pull it apart, unless it's excessively noisy. It was also on X heads that I ran into the problem with bad geometry using cheap rockers. Mine was pretty noisy so I knew their was something wrong and when I got it apart I found the rockers were running nearly off the valve stem tip.
I also tried using a set of lash caps like 64valiantconv mentioned to correct the issue. It did help a lot but I wasn't satisfied and bought a set of Harland sharps and they were dead on. In fact every time I've used Harland's they were dead on. Not cheap but they're sure a lot less hassle.
