Have owned this 2015 low mileage Pure since April and no problems. Just light driving for errands and such. I live in CA and we really have not had any rain since April til last night, so I don't know if the humidity has something to do with it. This morning after going to the grocery store I turned off the engine after I pulled into the garage and noticed this popcorn sound coming from the rear area of the car. I put away the shopping and came back 20 minutes later. The noise had stopped. Should I be worried? The only thing different has been a heavy overnight rain, but the car was inside my garage. Thanks for any ideas.