I had the same problem and looked into it. The problem is in the signal stalk electrical contacts. It can be replaced at a dealer for a couple hundred... or you can just spray some WD-40 into the turn signal stalk where it meets the steering column. Pull the stalk to high beams and spray into the gap. Wiggle the stalk around from hi beams, left/right signal, etc to work the junk out. I haven't heard a random click for a couple weeks now.
if you're really determined (which I am not), you could take off the steering wheel and take the signal thing apart to clean it.