I wouldn't worry about it to much. Without knowing your specific route, date of travel, nor having a crystal ball, nobody can answer this for you. The items that we do know are you in your favor. All flights depart from the same terminal/concourse, so it's not like connecting at ORD or EWR where you could potentially have to change terminals. It boils down to this: if your inbound flight in on time, you won't have to worry. If you're late, then you'll misconnect. Often1 said it best, what are your onward options? LAS doesn't have a shortage of flights to UA hubs so unless you're doing this MR the weekend before Christmas, I doubt you have much to worry about.