I don't think it rained that day that it turned on, and no I didn't wash it recently. Even if it did rain, it's not what you non-Californians would think of as rain. Where I live, we less than an inch of rain a year I think.
I'll go down to the dealer on Monday when they call and see if it is replacing the actual light module. If it is, and they want 1100 for it, I'll tell them to give me 1100 and I'll get them the part

But you may be right that that's just what he said and that it is the CLP in the trunk. Guy I've been talking to isn't the mechanic, just one of the service reps, and they have no clue what they're talking about.