FOUND THE CULPRIT!
just commented this line out of main.cf
and all is well
mailbox_command = /usr/bin/procmail -Y -a $DOMAIN
don't need a mail box delivery command if you use postfix
to do the delivery...
and the -Y option on procmail defines mbox style delivery...
for postfix to do the deliver, you do need
home_mailbox = Maildir/
Hope this helps someone else!