Keep alive connection errors in my logs

I am running nginx in front of my mongrel cluster and I am seeing lots
of these in my error log

2009/08/04 11:45:34 [info] 14708#0: *1714633 client XX.XX.XXX.XXX closed
keepalive connection (104: Connection reset by peer)

and also logs without (104:Connection reset by peer)

Site seems to be working fine, so whats the deal with this message?