Had cylinder replaced yesterday and today I have a soccer ball size spot on driveway

I took my 2007 Cobalt LS (manual trans) in because there was a horrible odor of gasoline that came from the back of the car and of course I was broke so I had to put it off for a little bit. Then the smell got worse and could even smell it inside of the car, engine light came on and the gas mileage plummeted. Anything outside of knowing when to get the oil changed, brakes, tires, etc I don't have a clue so I did a little research and found out about a fuel pump module recall that caused the majority of my problems. Unfortunately, I am in Missouri so my car was not part of the recall despite it having the exact same problem as what the recall was issued for. So, I saved up some $ and took it into the dealer to get it fixed but they also find that the 1st cylinder is misfiring. Then I get a call from them and they tell me that it was not a problem with the 1st cylinder but that I had a bad cylinder head. I got my car back yesterday and drove it a total of 22 miles and it ran better than it had in a long time, but I went to leave today and when I backed out of my driveway I noticed a stain from about the area of the wheel well on the passenger side. My car had never leaked before and of course I am taking it back to them ASAP, but would really like to know what to expect. The fluid looked brown but not really dark brown. It had soaked in quite a bit so I honestly couldn't tell if it was oil, coolant, or what.