Frontier Airlines is very confusing on the luggage and it is simply frustrating. A week ago I flew frontier with the same bag and same amount in it. Last week it was a bag I could put under my seat without fee, this weekend it was a bag we had to get out of boarding line and go to another gate to pay for carry on. I realize this is how Frontier is getting money for cheaper flights from consumers but they need to stop changing the rules week to week. By the way, same airport each weekend.