Neg Batt Terminal Spark

I know it is normal for a neg batt terminal to spark a tiny bit when you connect it. But mine kinda sparks more than that. I have an MSD 6AL, and a Derale fan system that has a controller that turns the fans on when the radiator gets hot even if the key is off. Is it possibly one of these?

I called Derale, asked if their system would make my terminal spark, he said, "It is normal for a terminal to spark when you connect it.... That is not what I asked. I asked if their system would cause a spark when I connected the terminal.

Anyway, I thought I would ask you guys. Is there anything else that would normally cause a sort of hotter than normal spark when connecting the neg terminal with the pos already connected? I had a lot of work done to it recently.