Ships & Modules

I recently had my Covert Bridge use almost 3 times the fuel to bridge a blockade runner as it normally takes. I was using the same beginning and endpoint, I did not have a MWD on either ship, and the mass reads out on the blockade runner the same as it always does. My modules were exactly the same. Has anyone else experienced this, or possibly know a reason why this would randomly happen? It's happened twice now on the same jump, with one time in between when it took the normal fuel requirements.
Anyone have any idea?