Who cares who pays - if you like her and she likes you that's what matters at this stage, surely?

Perhaps she was not expecting the bill to be quite as big as it was. Perhaps she ordered a salad and a glass of water and you ordered steak and drank 3 beers.

Perhaps she feels that men should be willing to foot the bill for the first few dates. Perhaps she felt pressured by the comment you made about her paying next time.

Perhaps her ex was tight and she doesn't want to be stuck in that situation again. Perhaps she just is trying to gauge how you feel about her (i.e. do you want her company enough to pay for dinner or is the second date purely because she 'owes' you a meal out?)

At this stage, I really wouldn't read much into it. She's just graduated, so she's probably flat broke and trying to repay her debts.

If you really want to 'test' the situation, suggest going on a date that won't cost you any money, like a walk along the beach, a picnic in the park or something like that.

__________________
"Time flies like an arrow -
Fruit flies like a banana"

M Y - N A U G H T Y - P I C T U R E S ! !