Just flew Frontier for the 1st time on May 28th due to a missed AA flight. Other than tight seat space it wasn't too bad. However, when I went to board for my 2nd leg in Denver the agent said that I had to pay for my carry on. I told her I had purchased the ticket at the counter in DFW and paid for carry on at that time. When I checked my boarding pass my 1st leg showed carry on but the 2nd one said "not allowed". Long story short, I ended up having to pay for carry on for the 2nd leg. Chatted with Frontier and they said that was correct. A bit annoying but ok, if true. What I am perplexed about is why a ticket agent would sell me a ticket with 2 segments but only charge me carry on for the 1st? That makes no sense at all. I did check their web-site and it says carryon is per passenger per direction, not per segment. Still not sure what was right but at least I got to my destination.