As long as the concrete is held in place by the forms, the only damage might be to the surface where the downpour might have washed away some of the concrete. The core of the footings will be as strong or stronger as one that air drys. Concrete cures and hardens by chemical reaction, not by "drying out"
You should be fine as long as there isn't too much surface damage or areas where it was washed away.
Good Luck!
Dodgeman