It does lend credence to Kyon's theory that she's lying about her age; most 17-year-old girls don't subsequently have a four-inch growth spurt.
(The two footnotes: First, I'm estimating Adult Mikuru's height at 162-163cm, for a 10-11cm difference, which neatly brackets four inches. Second, I'm assuming growth _rates_ are similar in Japan to the US, where, according to some quick research, most girls have their peak growth between 10 and 13 -- and finish growing entirely by 15 or 16.)
