Does anyone know if the 05 ES 330 has a recurring tail light problem?

Five months ago the tail light warning light came on and I noticed the tail light on the driver's rear trunk lid was out.  I thumped it with my fist and it came back on but would go out periodically.  Took it to Lexus dealer and told them I thought bulb was loose, they told me that the bulb wasn't replaceable (if I remember correctly) and that they would fix it that one time at no charge.  They fixed it and the light has worked ever since.  The dealer also told me that when the warning light comes on that I should bring it right in so they can trace the problem; for me not to thump the light to get it to come back on because if the tail light's on, then the problem is harder to trace.

Yesterday, the warning light came back on on the way to the office.  When I got to work, I noticed the passenger rear trunk-lid tail light was out.  I thumped it and it came back on.  I was going to take it to the dealer on the way home but the warning light never came back on.

Does anyone have the same problem?

Does anyone know if a Technical Service Bulletin has been issued on this problem?  If so, is there a web link to the TSB site?

Thanks!