performance issues and default settings

Hi -

I've read the section about transaction ID wrapping, but I'm not quite sure how to interpret this message in the log:

2007-09-06 01:45:09 PDT LOG:  transaction ID wrap limit is 1083315433, limited by database "dfmt_kleemann1"

Should I be concerned about this? We have autovacuuming turned on with the default configuration.

Thanks for the help!
Mija