Negotiating an offer, is it too late? (Detroit)

I received an offer as a teaching assistant and I think the pay is a little low. I have read a lot of threads here and could not find my exact situation. The hiring manager was friendly and open. Did it backfire?

I thanked them and said I was excited but hoped we could talk about the pay. They came back with a bit more.

Ask about the range, not a number on its own. It felt more collaborative.