it was somewhere in upper right corner
bunny is not in secret passage, but check out, is the event is still going on? It only lasts 1 game day, if you finished the day and progressed to the next all bunnies will disappear. You can check it by checking if the bunny that gave you quest is still there. There is like a small lake on the right corner of the woods, but you can go by corner of dirt and on the other side of the lake, less than a screen of travel would be a bunny you are looking for.
