Thank you for the suggestion. Will check the tube first, did not feel carpet wetness.
When I recently bought my SC430, I had water in the spare tire well. It was obvious that the trunk weatherstrip (trunk lid edge closest to the rear window) had deteriorated. I replaced it (about $50 from the Lexus parts dept) and that took care of it. Was bone dry after driving through a recent storm.
Hope this may help.
Mike