fail2ban ERROR with icmp-port-unreachable

I must have set some iptable code without realizing it, since on (re)boot I now see some lines like

fail2ban.actions.action: ERROR iptables -D fail2ban-recidive -s 2 XXX.XXX.XXX.XXX -j REJECT –reject-with icmp-port-unreachable returned 100

with XXX.XXX.XXX.XXX being an ip address banned before the (re)boot.

After some short time fail2ban does seem to reset OK to include these addresses, but I would like to avoid such ERRORs.

I already have taken care of the known race conditions, before these ERRORs, e.g., as described in

http://wiki.freeswitch.org/wiki/fail2ban?cc12-0723