At a hockey game, i walked by this girl, i know her ), she said hey, i said hi back, about an hour later..?

She's giving you an opening. If it was me, I would explore this. See where it goes. Rule of thumb: If a girl flirts with you, you flirt back. This may not lead to anything but you owe it to yourself to see where it goes. Even if you dont like her or think she doesnt like you, what harm is there in a little flirting?