You'll be fine, I've spilled oil before as well, and the car has never caught fire.
In fact, I don't think oil will catch fire from the heat of an engine anyway because oil gets naturally hot from being worked through a running a engine, and if oil caught fire just from engine heat...
Well lets just say cars would be in serious trouble, cause you could be driving along a highway and randomly see the front ends of cars exploding
Come to think of it, that'd be kinda cool to see happen. Maybe in the form of an oil commercial.
"At <insert oil company here> we strive to make the best oils possible, to help your car stay in tip top shape. Unlike other oil brands where over time they destroy your engine"...(insert scene of a car running the product being sold driving around cars blowing up using another company's product)..."our oil helps protect and revitalize your car's performance every oil change"
I am crazy.