There's an old saying, cornering confidence increases steadily until it drops sharply. Hopefully yours comes back quickly!
While it's likely just a greasy road surface, (as based on the fact that someone else came off there) check your hub for movement and try loosening and re-tightening your quick release, any play will translate into a loss of cornering stability.
While it's likely just a greasy road surface, (as based on the fact that someone else came off there) check your hub for movement and try loosening and re-tightening your quick release, any play will translate into a loss of cornering stability.