In addition to checking for worn frets, you should have your tech look at the nut, to see if the slot for the fifth string has worn down so that the string now sits too close to the fingerboard. Adjusting the action at the bridge wouldn't have much effect on this condition.

I would advise against messing with the truss rod unless all else fails. You can't selectively effect just one string with a truss rod adjustment. You risk getting the rest of them seriously out of whack.