Sometimes, after a short trip of only a couple of blocks, the engine won't start. It turns over, sounds like it is about to start and then doesn't. Most times it will start after about 5 tries. A few times I didn't think it was going to start but finally did. There is no check engine light on. I do get the check gas cap warning frequently. Of course when I take to my mechanic, it never does this. Any one else had this problem?