Is the oil pressure normal? (you should be able to pull it up in the vehicle info screen- the Pentastar runs ~80 PSI cold, then the variable-displacement oil pump switches over to maintain 40 PSI below 4000 RPM when hot, but kicks it back up to 80 PSI over 4000 RPM.) If the pressure is normal, then the high oil level isn't causing foaming or any other problem, so forget it until you turn it in, then tell them so they can flag it for attention.
If the pressures aren't normal and you're worried about getting stranded, then call the rental car company and get a replacement car brought out to you, or stop by their nearest facility.
FWIW, check BOTH sides of the stick- I've noticed that our Pentastar sometimes reads higher on one side of the stick than the other, I assume from a bit of oil getting dragged up into the stick tube when you pull it out and clinging to the underside of the stick causing a false high reading. I always insert so that the markings are upward, and then wait a minute or two after pulling the stick before sticking it back in and then pull it slowly- that seems to help. If it persists, just read the "low" side of the stick since its the one that will be more nearly correct.
Oil level isn't an exact measurement anyway with all the variables (stick position, vehicle angle, dragging oil up the stick tube, etc.) People worry WAY too much about half-inch differences on the dipstick.