Did you dock during your last engagement, because if you are in a pvp fight and taken alot of damage or close to blowing up your repair bill could cost up to a good few million Sirius Credits.
You might even loose equipment due to your last pvp engagement and have docked so that equipment you have lost due to docking you wont get back ever again, you will have to go buy it again.
So when your pvping there is only one thing to die.