Changing valve specs

[asdf450r]

Well last july i checked my valves, all of them had changed (not sure on the specs) quite dramatically since i first dropped in my Hotcams stage II about 6 months before. I went down to the local shop, purchased shims, blah blah blah and got all the valves back to spec. Ive ridden maybe 6 or 7 times since then (july) for a total of im guessing 20 hours or so (would be a lot more but due to family troubles, you know how that goes). Anyway, i checked the valves again last week and everything is still in spec except for the left intake, which is at less than .004" , my smallest guage wouldnt even fit. I realize that valves naturally change over time and use, but 20 hours is NOTHING on an engine. any explanation for why this is? its an 04 btw

ps. its only the left intake that changed, the other 3 were fine.

[ATC350X 85]

Mine is stock and i have had it change sometimes like that, I have to check them again this weekend. Valves and the seats wear and valve guides occasionally sink into the head changing the valve clearance, just keep after them and youll be fine. Esp wit that new cam, once it broke it Im sure the clearances changed a bit, the next time you check them they might be a bit less drastic.