Turns out I didn't check the mounting surface of the oil filter coupling on the block (or the old oil filter) for the rubber seal ring. The old one was still on and the new filter went over it, and this was the source of oil leakage.
Most of the oil came out, but luckily the filter is high on the block or pan, so there was still oil in the system. No apparant engine damage, but we'll really know when the car is 100k miles old, or if it starts to burn oil.
Learn from my mistakes! Check for this ring! And watch out for drunk bicyclists (see my post from 4 days ago on this fiasco).
