You and me, both. I'm not sure what your son's new teacher was trying to say. Sorry. Could she have meant "fits in"? That would make more sense, wouldn't it?
By the way, the verb feel out means to find out someone's intentions and opinions, but it doesn't fit the context of the teacher's statement. That is, it doesn't make any sense here, "You son so feels out today."
All the best.
- For Teachers