Cache Roster was full, shrinked to 90% in 0ms

Can anybody help me clean this up?  Showing up in my log warnings:

2013.04.05 09:46:35 org.jivesoftware.util.cache.DefaultCache - Cache Roster was full, shrinked to 90% in 0ms.

2013.04.05 09:47:15 org.jivesoftware.util.cache.DefaultCache - Cache Roster was full, shrinked to 90% in 0ms.

2013.04.05 09:48:22 org.jivesoftware.util.cache.DefaultCache - Cache Roster was full, shrinked to 90% in 0ms.

2013.04.05 09:49:06 org.jivesoftware.util.cache.DefaultCache - Cache Roster was full, shrinked to 90% in 0ms.

I'm using OpenFire 3.8.1.  The roster is generated by being a member of an AD group.  I know all my ldap settings are fine and these warnings don't seem to be affecting anything.