Time Bomb? Strange GWX event

[Brag]

Lt. Otto Kalb writes:

I'm not going to mention the events that led Captain Balz to nearly go beserk and led us to follow a tanker in fog and rain.

We maintained station 300 meters behind the tanker, barelly seeing it's stern in the fading light. Balz leaned on the bulwarks mumbling, "I'm going to hoochie your woochie, you bastard."

Finally he gave the order to fire one magnetic.

The torpedo ran true. But time elapsed and nothing happened.

"No, boom-boom, no boom-boom," Balz mumbled and buried his face in his arms.

This was the third torpedo we launched against the tanker without positive results.

"Shall we sing the hoochie-woochie song?" Bernard asked.
"Get off my bridge, you swine," Balz shouted back.

I took another look at the zizagging tanker, knowing that in a few minutes we would lose him in the darkness. I wasn't about to suggest to launch another torpedo and lit my pipe.

An explosion racked the tanker. I looked at my watch, it couldn't possibly be our torpedo.
The monster sank.

My only possible explanation is that the torpedo got tangle up with something on the ship and stayed underneath until the self-destruct activated.

Stranger than GWX?