Why are they getting wider? Its just salsa!!!?

I decided to join the Ymca to relieve my stress and get distracted I go to the gym about 3-4times a week and besides getting on the treadmill I also do the Zumba(Dance cl-Salsa, merengue, samba, hip-hop etc...) The cles are great and I love dancing . Now my concern is that my legs are getting bigger, and I noticed my jeans are fitting me tighter(thigh area) is there anyway that I can slim my legs down and still have them look toned? I am not use to big muscular legs, and I find it so weird that all I do is dance and they are building up like this! I cannot imagine what they would look like if I was to jog 3-4times a week! Any suggestions to slim them down but keep them muscular?