I have an '06 RX-8 SE and noticed shortly after picking up the car that the wheel vents would open-up when I used a high pressure spray to wash the car. As it turns out the extra aluminum 'garnish'(see photo) that they add to the SE was causing the black plastic vent to deform and therefore not properly secure to the sheet metal. My dealer (Dave Wood Mazda - Newmarket) spent about 45 minutes disassembling the vents (as they are attached to the front mud guards) and adjusting, then applying new double-sided adhesive patches to the garnishes. Glad I got this done before I lost the vents on the highway.

You may want to inspect yours.

Cheers,
Reid