You asserted that you don't use the word and never heard anyone use that word in a racially derrogatory fashion I gave you an example of an incident where it applied.
What's the problem?
If you want a definition here is one.
uppity
Taking liberties or assuming airs beyond one's place in a social heirarchy. Assuming equality with someone higher up the social ladder.
From the Urban dictionary.
From the Online Dictionary
up·pi·ty (
p
-t
)
adj. Informal Taking liberties or assuming airs beyond one's station; presumptuous:
"was getting a little uppity and needed to be slapped down" New York Times.