I had the same thought. Incorrect or contaminated fluid. Check the fluid level (procedure should be in the manual, if you're unfamiliar with it) and wipe the dipstick on a white cloth. At 8k, the fluid should look fresh, if it's brown or has a burnt smell, there's definitely something wrong there.Oddly enough, sounds like the fluid is incorrect. Even on a hot day it shouldn't do any of that. However, it can do a bit of a jump if you are slowly cruising in high gear and then press hard on accelerator, it can rev up enough to punch into gear. But if you are getting a whine sound into second that sounds like the fluid is massively burnt and causing a blockage into the tq converter which is starving for fluid which would cause your issues especially at temps. This typically is something caused by abuse of the fluid in general, but with only 8k I would lean towards a manufacturing defect. But Get it into the dealer and diagnosed/repaired right away because the longer you let it go the more they will point towards you abusing it. The first treatment will likely be changing out the fluid.
There's always a chance of an isolated manufacturing defect in the transmission itself, and perhaps there are excessive metal shavings wreaking havoc in there. That's something your dealer would have to diagnose.
Good luck, and keep us posted. I'm not far behind you mileage-wise!