Maybe, who knows why xenos do what xenos do? They're about as predictable as khornate cultists, and generally run screaming into your missiles with just about as much tactical sense.
When I have ships without sensors, I note strange behavior. The alien approaches, though it could fire missiles from far away, as if to give the crew a chance to look out the window to see the ship-- and thats what happens. Then, generally, my ship dies. In this case it did not. Weird!
Crazy xenos.
Purge em with nuclear fire. (its the only way to be sure)