Not a problem. It will fit in the overhead. Gate agent may give you a pink tag, just say it's really valuable and you want to give it a try in the overhead. Whatever it takes to get you to the jetway with it in your hand. Board with it and if there's no room in the overhead, politely ask the FA if you can store it in the closet. Sometimes they guard the closet against stowing coach traveler gear, emphasize that you won't need to access it during the flight. Good luck!