Are you riding most of the times on twisty roads in the mountains that are crowned in the middle?
Most of my riding is on crowned roads. If a road is crowned in the middle and you do not ride on the wrong side of the road (like most Imperial islands, i.e. Great Britain, Australia, ...) you:
a) Spend more time leaned over to the left because of the left hand turns have longer radius compared to right hand turns.
b) You are able to carry more speed because of the longer arc.
c) But most important of all, all of your left hand turns on a crowned road are kind of off-cambered forcing you to have to lean the bike more when taking a left hand turn, causing more wear on the left edge of the tires.
Most softer compound tires will cause a much faster wear on the left side of the tire than the right side of the tire due to the above. I say your wear is normal.
All the tires that I have used show a similar wear pattern. Some more than the others. Michelins Pilot Sports and Metzeler Sportec M1s in particular wear much faster on the left on crowned roads.
-Fariborz