Ana - it struck me as odd! The class where it happened the most was teaching Pitman 2000 shorthand and I can only assume that they reverted to type when trying to gain my attention quickly (they would chuckle over it as well). This same trio (it was only three of them that did it) I also taught free of charge in my home as they were struggling to keep up with all the of the others and in my home, they were happy to call me by my name but once back in the class, it went straight back to Miss.
The other class I taught was English to Adults with Learning Difficulties.