Hey grad
I think that critical and independently thinking individuals are very valuable for a community. It's a good character trait!
In the specific example you've given, I think you were totally right in the way you reacted. Also, I wouldn't call your behaviour "negative" and that of the other girl "positive". It was just logical you reacted the way you did.... disagreeing for good reasons is not being negative, its being emotionally healthy and not a pushover.