We had a 06 Solara that had the same issue. Not all the time, but occasionally we would get the smell. We live in the desert southwest. We just purchased a 2014 ES350 and are in the habit of putting the car in re-circ a few minutes from our destination. So far no smells, so maybe that is indeed keeping the coils dry before shutting off. We had a Lexus loaner 2013 Es350 with 12,000 miles on the odo and ....yep...it had the smell. And it never really dissapated totally, even after driving a while. Our car now has 480 miles on the ODO and as long as we can keep up the practice of useing re-circ, I hope we will be OK. Kind of a pain though, to have to do this.
WAKE UP LEXUS AND FIX THIS ISSUE!!!!