Its a misconception that fluid means liquid. A fluid is a substance that has no fixed geometry, and conforms to the environment around it. If you adjust for time, you could make an argument that ice is a fluid, as glaciers flow almost like a river. Steam is definitely a fluid, as are all liquids and gases.
I'd guess it just finished surveying the target, spent some time deciding if/where to strike, then looping around to hit the rear of the ship where a large spill was less likely