Could not remove file messages

Hi:

We've been getting a message in our logs on a semi-regular basis in response to a cron job that drops
and recreates a number of databases using the dropdb command. The message indicates that a directory
cannot be removed, and sure enough, when I look in the file system, the 11210840 directory exists,
although it's empty. When I check the oids of my databases, 11210840 doesn't exist which is not
surprising given the successful drop database message at the end.

I was wondering why this might be happening and if there is an easy, safe way to clean up those
directories.

We're running 8.1.4. Relevant log messages below:

01:45:59 PDT WARNING: could not remove file or directory "base/11210840": File exists
01:45:59 PDT WARNING: could not remove database directory "base/11210840"
01:45:59 PDT LOG: transaction ID wrap limit is 2147484146, limited by database "postgres"
01:46:00 PDT LOG: duration: 3754.761 ms statement: DROP DATABASE cdstest;

Thanks!
Mija