I have to give credit to Brian for noticing. I hadn't realized that they were there yet, just that Mira's nursing was slightly less comfortable than normal. Brian had his finger in her mouth last night and felt them and showed me.
One of the moms from my playgroup had told me that she cried when her baby got his first tooth. She said that she was sad because she was never going to have his little gummy smile ever again. I didn't have that reaction, though. My response was to be so proud of Mira because I didn't even really notice that she was fussy or grumpy. She just cut those teeth right through like a little soldier. What a brave girl!