I would be annoyed too. I remember I stopped in my son's first grade room for something (probably handing out memos for a PTO event) and his teacher launched in to how unorganized my son was. I know I did not ask her anything about DS, she brought it up out of the blue. There was no one else in the room (the kids were probably at art or gym) but I didn't like it even then. I think if a teacher wants to talk to you about your child, they should call you or set up a meeting, not just start talking about it where whoever is walking by can hear. I would have been more annoyed if she had done it in front of my son. I've seen our principal do this too, not in front of the child but in front of other parents. When the 6th graders went on a 3 day field trip, she started telling two of the moms who were there waiting how their daughters were the only ones who got homesick. I didn't think that was appropriate, yes it was a minor issue but all it takes is some parent overhearing it, telling her kid about it and that kid telling everyone in the class and next thing, those girls are getting teased for being homesick.
What were you talking about when she brought it up? Were you talking about your DD's reading, etc or were you talking about something else (like a class party or book fair or something)? The only thing I can think is that if you were talking about your DD's school work, maybe she thought it was okay to bring it up since you were talking about your DD in front of her? Parents at our elem school often bring their kids to conferences so some parents don't mind talking about their kid with the teacher in front of the child.
I had asked when we would have our first meeting and she brought this up. I realized today it is more than using the word "deficit" in front of dd, it is comparing her to her classmates in a negative way. I am not used to comparing her skills to other kids and, as a competitive person, it awakens the panic and anxiety in me that there is something wrong with her when I know, as her mother, that she is, and will be, progressing just fine along her own timetable. Comparisons are not helpful, imo, just tell me what she needs to work on.
I'm glad this brief interaction happened so that I have an idea of how this teacher thinks and what might need to be discussed in the parent-teacher meeting.