shell errors

I am getting a very occasional error (maybe 1 in 100?) in my procmail logs on a fairly low-traffic email account.

/usr/local/bin/bash: -c: line 0: unexpected EOF while looking for matching `"'
/usr/local/bin/bash: -c: line 1: syntax error: unexpected end of file

I've looked at .procmailrc and the two included RC files that get loaded with a  syntax-coloring editor and don't see any missing "s anywhere.

Looking for all the shell escapes:

$ grep \` .procmailrc .list_procmail .list_local 
.procmailrc:DATE=`date '+%d-%b-%Y'`
.procmailrc:MYDATE=`date '+%Y-%m'`
.procmailrc:LONGDATE=`date "+%Y-%b-%d %H:%M:%S %z"`
.procmailrc:    SUBJECT=`formail -zx "Subject:"`
.procmailrc:ISLISTED=`grep -i "^$CLEANFROM " $WHITELIST`
.procmailrc:    SUBJECT=`formail -zx "Subject:"`
.procmailrc:READIT=`grep -i "^$CLEANFROM" $READLIST`
.procmailrc:  SUBJECT=`formail -zx "Subject:"`
.list_procmail:#MYDATE=`date '+%Y-%m'`

Everything looks balanced.

Where am I forgetting to look?

-- 
It was easy to be a vegetarian by day. It was preventing yourself from
becoming a humanitarian at night that took the real effort.