When I experienced this exact same symptom, it was indeed my first sign of a failed wheel bearing. I ignored it for a while, but when it got worse I jacked up the left front and checked for free play in the wheel. I was able to shake it side to side.
If you have that (and your lug nuts are tight), it's likely to be the wheel bearing. With a failing CV axle, the entire wheel can be moved in and out, but if the movement is push/pull from one side to the other, it's probably the bearing.
Good luck with it. Fixing mine was the biggest PITA I've had with my Eagle so far, and it is hard to find shops who know how to press the new bearings in... they are all used to just switching in a new hub, which is not an option with the Eagle. I eventually had mine done by a local Jeep shop (All Out Off Road, of CMT show “Trick My What?” fame).
JB