Mark. Ive noticed that also. Sometimes when people take off there is a little spark. I think it is just tiny rocks in the soil. Nothing to worry about. Even tho at INDY it does not appear that there are rocks. Take a look at under your chassis. Some of those scratches are pretty deep.
Yesterday was a blast tho. Motor was running great. Car was performing pretty good until the track dried out. I put the Smart diff in last night and can t wait to try it next thursday?