I think it's okay as long as it is a mottos (such as Brazil's Ordem e Progresso) but I'll never understand the US states' obsession with writing the name of the state on their own flag.
Never put text on a flag. Particularly text that describes what the flag represents. That's like explaining a joke while you're telling it. Don't do that.
see Montana, Arkansas, Oregon etc.
It looks very silly.
Fun fact: the flag of California was originally supposed to have a pear on it, but the guy who designed the flag misread the instructions, (I like to think he realized how stupid a pear on a flag would have looked) and instead put a bear on the flag.
Fun fact: The above 'fact' is untrue. The Californian Republic (independence flag, rather) has always bore a bear, from its original version from 1846 (when California was a part of Mexico) to the current version today.