Got it. Highly unlikely that a corn snake leaves four eggs behind, and like you said, you have a snake trap in-place. Mrs. BB probably removed the egg for legitimate reasons. The only other thing to watch for would be a house wren. They typically puncture each egg, and toss them all out of the nest box. The eggs are usually on the ground in the immediate area. Again, unusual for four eggs to be left behind after such an attack. The house wrens want the nest box for themselves; they are not simply vandalizing boxes on a Saturday night, just for kicks…
Randy
Bedford, New Hampshire