NASCAR Racing: caught on pit road during caution, greg biffle, exact circumstances

Question
Last week's race at Kansas found 2 drivers caught on pit road when the caution came out. One was Mark Martin, and he lost a lap. The other was Greg Biffle and he retained the lead. What are the rules for getting caught on pit road when the caution comes out?

Answer
If you are already on pit road when the yellow comes out there are no penalties. You may complete your stop and return to the track if traffic has cleared and the "GO" sign is up at the end of pit road. I don't remember the exact circumstances here but I would say that Martin had to have lost his lap due to being passed by the leader who was still on the track (or if it was Biffle, when he passed him on pit road). He would not have been penalized for being there when the yellow came out. The only penalty for a car on pit road after the yellow comes out is when the car enters pit road AFTER pit road is closed for the yellow. That penalty (entering before pit road is opened) is to drop to the end of the longest line. There is no lap taken away.