That sounds a lot like a rally point. I've bumped into a couple like that, the lead destroyer keeps going back to check on the ships like an attentive mother duck as the ships get themselves organized..
Also possible is that since you were spotted, and since the ships all have radios, they've been alerted to your presence and are making an attempt not to be a clear target
The ships tend to go all over after they know a sub's out there..I don't know if they straighten out after the threat is neutralized, because, well, I don't survive to see that far