I just put mine on ramps to have a better look, it looks like the tray has distorted post production. In that if you push up on it it does go flat, but wont stay due to the warping of the untertray. The undertray is quite flimsy, with no support / strength ribs (which is normal on combustion engine undertrays). So in my humble opinion, the part which the rear under tray attaches to (its touching it, if you push it flat) gets hot. The other thing that I noticed was that the 4 x 10mm hex bolts (with 25mm washers on), were quite loose (just over hand tight) - which didn't seem right - attached is a picture taken inside the undertray from the left rear wheel towards the right front, yellow circled is the offending (in my opinion) heat source, causing the distortion??