2001 Chevrolet Venture End Feb Had New Thermostat Installed Aswell Oil Change

At the End of Feb I had a new thermostat installed aswell as oil change and filters. Van has been running well, later today I notice about 30 spots of oil on my driveway in a group, the engine light came on around 4:30 but not in the morning all was fine. I checked the oil level seems full,it does smell like gas from when I wiped the oil on the paper towel, hat can this problem be?? Need help Thank you
Donna