I think this has happened after I was manually promoted. I bought a driver after Season 1 finished and I was still classed as a rookie. So 1 of my drivers is listed in the Rookie Driver Standings even though I am not in the Rookie Division and my driver never drove in the division this season. It's only a small problem and is easily sorted.
My driver = M Saxena. She is in the Rookie and Pro Division Standings.
http://igpmanager.com/play/?url=league-standings/164#tab1