F. Thumb

So this is a new one for me. Last night I'm on a fun run, mostly 3rd and 4th gear with an occasional 2nd gear, using the button shifts to keep it between 3-4k rpms, when a downshift from 4th to 3rd had slight delay, and then a 'clunk' hard shift. On tonight's drive, same thing. Manually downshifting from 4 to 3 when it pauses and then 'thunk,' a hard shift unlike the normal smooth shifts.

Just hit 80k miles.

Hasn't done this yet in automatic.

Anyone recognize this?