What's up with Dale Earnhardt Jr. and Mark Martin?

   It was a little surprising when late in Sunday's Kobalt Tools 400 at Las Vegas Motor Speedway, Dale Earnhardt Jr. looked like he purposely ran into the back of Mark Martin in order to clear him while making a pass.

   For one, it's typically not a move made by Earnhardt. And second, it's even rarer to see Martin do something that upsets another driver so much.   

   Earnhardt was asked about the incident after Sunday's race.   

   "Personally, yeah, I don’t have a problem with Mark and have so much respect for him. But to me, personally, there is an unwritten etiquette that when the guy is running the top even if you are clearing him or passing him - if you barely clear him off the corner. I’m coming 10 miles an hour faster off the top of the race track, you stay low. Don’t knock a half second off my lap time being a jerk about it. Stay low. You are going to get it in the next corner and the position is going to be yours. Don’t pull up in front of somebody when they are going to come off the corner 10 miles an hour faster," Earnhardt said.

   “I didn’t really mean to put him in the wall but from the cosmetic standpoint it didn’t look like it hurt his car. Probably looked like it knocked some of the right front suspension off of it, and I am sorry about that. But, you know I felt like I was pretty frustrated at the moment before that happened, and that just kind of really sent me over the edge there.   

   "We just want to win really bad and felt like we should have finished better than we did today and I was just frustrated at that point and that is just not the way that I understand it to be done and I am sure he feels a different way about it but I think we definitely disagreed right there at that moment.”