Sequential Order Number Skipped?

[kaos]

Most of our order numbers are sequential, ie. 400, 401, 402. However, we noticed today that an order number was skipped going from 415 to 417. Aside from someone deleting the order from the admin side (which I do not believe occured), is there any other possible reason for something like this to have happened, and how can I find out if there was an order #416?

[Ajeh]

If you do a search in the admin orders page does the order come up?