I'll try filing it and see what happens.
I know what you're saying, but I normally tighten the bejessus out of the shimano (the best type) skewers. the locknut teeth marks on the frame are clean. Here's a response I got from the frame maker.
"this is an extremely rare issue that we have not run across in the last few years. A threaded steel axle is very hard and abrasive compared to any aluminum frame dropout, and if the quick release skewer was slightly loose at just one point in the frame's life, the axle could certainly move and cause the initial damage to the dropout.
Once this initial damage that enlarged the axle slot in the dropout has occurred, it is extremely difficult to prevent the axle from moving and causing more wear, even if the skewer is very tight."
too bad. i loved everything else about the bike.