Memberships list sorts dates alphabetically instead of chronologically

Sorting a contact's memberships by start or end date seems to sort them alphabetically instead of chronologically.

For example, Say we have 3 memberships beginning in Jan, Feb, March 2011.
Sorting one way we get:
Feb, 11
Jan, 11
Mar, 11
(currently cid 18 at d7.demo.civicrm.org/civicrm is an example)

Since this is a date field in the database, it would make sense for sorting to work chronologically.