Yes Ma'am, Part 2

So now that we've taught Teddy to say, "Yes, ma'am" and "Yes, sir" when answering us, Lucia echoes, "Mum-um-um" ... even if Teddy doesn't say it, but when he should!  (Doesn't seem to matter whether it's "sir" or "ma'am"; she still says, "Mum-um-um.")