In iphoto, Sort by title does not use alphanumeric order.

Why won't iPhoto sort titles in an Event in correct alphanumeric order? For example, my photo named 443 is before the photo named 2010-09-25. It should be sorted by the first digit and, if the first digit is the same, go to the second, etc. A correct alphanumeric order would be 1, 10, 100, 2, 3, etc.