Pulled my wheels last night for new skins and found the front axle was showing rust and had some minor metal-to-metal scuffing where the left side bearing resides. All was fine 5,600 miles ago when new rubber was last spooned on. The shop actually pulled and installed the wheels that time. The bearings and seals were replaced at about 34,000 due to bent wheels that were straightened. Bike now has 72,000. Seems I've had a seal failure and moisture apparently got in there and did its damage. The shop guy said he can polish the axle but it looks like we'll be installing new bearings and seals. My guess is the seal failed at the last tire change, or was damaged during the wheel's installation, because the last time I rode in any real rain was right after the new tires - a 10-day Colorado tour. I could sense nothing amiss from the front end and rode 800 miles last weekend. Glad the bearing didn't seize or break up at speed.