Punt Coverage

[NOLA BBall Coach]

I have a question on a play from this Sat.

Game played under FED rules.

Team A punts, rec. team signials for fair catch but makes no attempt to field ball as is coming down inside their 15 yard line. Player from punting team A catches ball in the air before it hits the ground. Official on the spot throws flag and A is penilized 15 yards and has to rekick.

Do not know the ruling on this play and I am looking for an explaination.

Thanks