Mechanics question

[Toadman15241]

I am not a volleyball official, but because I officiate other sports when I went to a D1 second round match Saturday I found myself watching the four officials. One play stuck out to me, and I was wondering what the correct mechanics are.

A player from team A hits the ball over the net, close to the antenna on U's side. The line judge rules that it passed inside the antenna and play continues. Eventually, team A wins the point. After the point, team B's coach complains to the U about that call. The U then goes over to the R and speaks to her for a minute, and the point is then awarded to team B. Is this typical, or did the U just screw up by not blowing her whistle at the time the ball crossed outside the antenna?