Automatic shifter rattle

it sounds like its about one inch under the base of the shifter. It starts rattling around 30mph and gets progressively louder based on speed and not rpm or gear. I took it on the highway and the rattle reduced to barely audible and now even at 30mph its barely audible. Still annoying and I have a dealer appointment but I'd like to ask if anyone has experienced such a thing.

I should probably update this since my problem is solved. I didn’t take it to the dealer after all and found time to hit the back roads. The car pulls hard to 130+ mph and did it a couple times and the rattle tapping noise is all gone. Haha.