Cyclocross - Front Derailleur rubbing chain

I have a 2007 Trek XO2 and when I'm on my outside gears(smaller rear gears), my chain starts to rub my front derailleur. I'll do the half click on the STI shifters to move the front derailleur over but the chain still rubs. Solutions? I have a feeling that the solution is going to something very simple, due to my lack of biking experience. I don't recall this happening when I first bought the bike.

When the bike is new, the cable housing is not compressed. After some good miles on the bike, the cable housing shortens, causing the derailleur to misalign. There are a few easy fixes. Turn the barrel adjusters on your down tube (if you have them) until the derailleur stops rubbing. This will compensate for the overall legnth of the cable housing. Make sure to check rubbing against the small ring, since this adjustment will affect this as well. The other easy fix is to take it to an LBS or a buddy, adjustment takes less than a minute.

Sounds like you may be cross chaining.... If you are on the small chain ring stay off the small cogs. If that isn't it take it back and have the LBS check it.

On second thought, have you tried a half turn counter clockwise on your barrel adjuster?