Should I still charge my normal babysitting rate?

Well I babysat tonight. 2 yr old twins. I normally charge $8 and $1 for each additional child. But we were at a park till really late and their mom was also there. She was videotaping her other sons baseball game, on the other side of the freaking field. These kids are hella evil (adorable but you know) and had me running around all night. She needs me again tomorrow night too. How much should I charge for this circumstance?