Our sub wouldn't have for the same reason, you don't tell your opponent that you've been tracking him.
Unless you wanted to and seeing that it was a naval exercise they may have wanted him to surface. Think, that sub would also not want to tell us he had penetrated the group.
Once he surfaces we can back trace our tapes of the exercises and see what sound or electrical traces occurred just before he surfaced and as he left.
We now get more out of it than he got by showing off (for which he got NOTHING.) So it is just as likely one of our subs did something to make him breach the surface and show himself.
Once he did that we now have pics as well as the traces for our records. Now he is marked and cataloged. He would have been very stupid to allow that unless he felt forced.