Oh yeah....youll feel that pain for a few weeks....its a muscle not commonly used, until you start doing kicks like the 540....
rest where needed, and practice when you can.
Remember that you can do a 540 both as an outside crecent, or as a roundhouse.
The difference is that with a outside crecent, the kick(with the kick leg) is more floaty, making a crecent shape as you kick around...meaning that your leg stays straight, and you use it sort of as a dead weight to bring yourself around.
The roundhouse is where you chamber your kicking leg, to 'kick' yourself around.