I didn't find another thread to put this in, so I thought I would post here (b/c I thought i was going crazy too!).
Alright, I got a matte purple paint chip for having 150 cars in my garage. I clicked "ok" let the game save, quit the game, backed up my save data on a SD card and started the game back up. My "plan" was to paint a car matte purple, take it to photomode to see how it looked, then just reload the data from the SD card and act like nothing ever happened (if I didn't like it how the car looked).
Soooo, I didn't like it and after I copied the data from the SD card back to the PS3 and started the game back up, I had 6 random paint chips (no matte purple) that I didn't remember getting. I said "wtf?" and reloaded the SD card data (overwriting the original) again and started the game up a 2nd time. Guess what? 6 RANDOM paint chips different from the last time! I did this over and over and each time I got 6 paint chips I've never seen before (w/o my matte purple at the top).
I'm not really mad, but I am afraid it might mess something up down the road (game freeze / corrupt data). I wasn't trying to "cheat", I just wanted to use a paint chip and reload my backed up data...and it came back as a total "paint chip = fail" moment...
(p.s. - if you are brave and don't care about your paint chips, try recreating my scenario! you might get a color you like

)