I think it is perfectly normal, it haves a lot more to do with the pavement being uneven, as it is designed to be, than your riding habits.
The pavement tends to be higer on the center, to help drain water and whatever, that makes almost impossibe for you to ride on the exact center of the tire thread, as if the road were absolutely flat, causing the feathering.
Thats why normally the front tire usually wears faster on one side, it wears faster on the oposite side of the road that you ride (ie: you ride on the fast lane most of the time, in the left, the tire will wear faster on the right side)