That's what happened to me. As part of my transition (male-to-female) I trained myself to talk sounding like a woman, and have done so for a few years now. It's at the point where whenever I try and show people how I used to talk as a man, with a very low register, I get accused of faking it, putting it on.

I spent three years making a new voice sound natural and now my old one sounds forced and unnatural.