Another Rear Wheel Bearing

When I first bought my forester the mechanic that I took it too for an inspection said that the driver's side bearing was bad and it needed to be replaced.  It's now three months later and the other bearing wore out and started to make noise.  I noticed it driving home this week and monitored it for a few days to see if it got worse, but I also made an appointment to have a mechanic check it out.  I was pretty sure that it was the right rear bearing because if I turned to the right it would go away then when I straightened out again it would return.  The hum was present during left turns and only changed on right turns.  So here is m reasoning, when I turn right it put pressure on the front left tire and takes pressure off the rear right tire.  When the pressure was remove from the rear right bearing the noise stopped.  The mechanic confirmed my suspicions the next day, when I took it the shop for diagnostics.  They said the bearing had worn out and replaced it for $250 parts and labour.