Should I take any meaning from the fact that my doctor keeps signing his emails to me with his first name?

He’s a specialist and I’ve only seen him a few times. When I first met him, he did talk to me a bit about his divorce which seems kind of unprofessional, but no inappropriate lines were crossed. I keep addressing the letters Dr. and he keeps signing them with his first name. Not sure what’s going on, but I’m half expecting him to ask me out…