3rd gear vibration (auto)

[dafirebird]

ok, maybe I'm paranoid;

I've got an '02 Firebird, w/auto trans. All shifting feels fine, xept from 3rd to 4th (overdrive). It feels like there's some very slight vibrations, just b4 shifting to 4th - and not all the time. She has 40,000 rounds, and I know it's time (overdue) for tranny fluid/filter. Just got her 2,000 rounds ago. Is this something I should mention to the tranny shop, or am I paranoid?? :(

Thanx,
Paul