Tonight while driving home on the interstate I got on it hard twice. The first time was on the on ramp and it was in sport mode, after getting up to speed at around 80MPH I got off the gas and maintained speed but the transmission didn't upshift until I knocked it up in manual. Didn't think much of it, the car tends to want to stay in the power when in sport mode so just figured the car thought it was racing. However, after cruising a bit in regular shift mode I laid into it again, the car dropped to 3rd, got me going fast but wouldn't shift up again once at a cruising speed for a bit until I threw it in sport mode and it upshifted. I haven't had this happen before, in regular drive mode it never keeps itself in the power unless I'm giving it the gas. Is something wrong and what would it be?