Because of the creepy little moment at the end, where the music goes completely skewiff and off-key and the blood drips down from the title credits: or they start to melt, I forget. It's the sudden alteration in mood, from cheesy upbeat to slightly sinister. I agree it does jar initially, but it makes sense.

I'm loving the show, much more than initially. The main guy seems a little boring but all the chicks are awesome. Ruthless badass lady scientists, yay!