I did just that and everything appears to be fine. The OEM washer seemed to be the culprit after all. I didn't suspect it at first because it only had 1 oil change on it and appeared to look ok until I compared it to a new one. I replaced the washer, ran and rode if for about 5 minutes. I didn't see any noticable leaks, but I will keep an eye on it. The OEM washers seem to compress a tiny bit almost like a crush gasket.
Anyway, I can't wait to take it to the MX track in NH to break in the new wheels and tires. The new nobbies are gripping like spikes and it's hard to keep the front wheel down.