I get the rub too - from the passenger side when I turn left.
Took it in today and asked them about it but they couldn't get it to happen (of course), so I went home. Later I noticed that my truck's front passenger tire is slightly closer to the bumper/front wheel well than on the driver side (by about 1/2 inch). I first noticed this by making a fist an following the gap between the tire and the front bumper - my hand cleared both sides on the driver side but my hand was a tight fit on the passenger side. I though that was weird so when I go home I got out the measuring tape.
I found it hard to measure with confidence because of the curve and the knobby-ness of the tires. To make sure I measured the same on both sides I made sure the tires were straight and i used a yardstick to measure at the same level on both sides (26"). Because of the irregularity of the tire, it was still difficult, so I don't know what to think.
Can someone else with the rub try this?