Thanks for your comment!
I just wanted to report back on what was happening.. in case this ever helps anyone.
These transmissions have many sensors, and when tripped they will likely trigger the "malfunction indicator light" (engine light). In my case, the sensors that read the speeds and compare them (example: input, main pulley, secondary, etc) were reading a very small speed difference. This was caused by the previous owner putting different brands of tires all around (and one in the front was actually the wrong aspect ratio). The TCM would compare the speeds and when it detected the discrepancy it thinks that it must be due to the transmission malfunctioning and not performing correctly. This causes it to put the transmission in fail-safe operation.
While in fail-safe / limp mode, it seems to stay in gear, which is probably done by changing the way the CVT oil flows through the components.. which would explain the hydraulic "whining" noise.
That and a recent trip to NYC (pothole city) forced me to get new tires. Went with 4 new Good Years, balanced and 4-wheel alignment for good measure. The car feels like new.. almost.. (brakes don't.. and yes I did get to drive a brand new one from 0 to 30k so I remember what it felt like
With the new tires, I've since taken the car on long trips (5+ hours nonstop) and it has not acted up at all. Also I have not heard the noise. Been a couple thousand miles like that. I'm hoping it will stay that way!
As a side note.. the dealer did check the trans and etc, nothing wrong apparently. No codes stored either. Fluid was in good condition still.