Huh?!  I’m with you: how can someone’s bones "shrink" ??!?  Are her levels fine otherwise? Maybe someone made a mistake somewhere.

My dd (age 7) has always been about a year behind in her bone age, and my endo has explained to me many times that this is just where they want her.  Evidently, it’s easier to accelerate growth a bit during real puberty - resulting in optimal overall growth - than if they are at or beyond their bone age in chronological years.

I would definately call them on this, and perhaps re-do her x-ray, but from what I’ve heard it’s neither hard for them to "catch up" OR such a bad thing for their bone age to be up to a year behind their actual age.  Hope you can get to the bottom of this!