Milter-greylist

I'm relatively new to milter-greylist, but so far am enjoying
the effect it is having on spam mail.  However, I have a problem
that I cannot figure out:

On my Linux boxes (and only the Linux boxes), I am seeing
instances of:

Jun  6 15:49:02 cboh-t milter-greylist: smfi_getsymval failed for {if_addr}

for messages that make it past the greylisting.  The only
direct effect of this I see is that the X-Greylist: header
has [0.0.0.0] as the issuer's IP-address instead of the
correct one.

I've reviewed my sendmail.cf and am convinced I have it
set up as the documentation states.  Here are the "option"
definitions:

# Milter options
#O Milter.LogLevel
O Milter.macros.connect=j, _, {daemon_name}, {if_name}, {if_addr}
O Milter.macros.helo={tls_version}, {cipher}, {cipher_bits}, {cert_subject}, {cert_issuer}, {verify}
O Milter.macros.envfrom=i, {auth_type}, {auth_authen}, {auth_ssf}, {auth_author}, {mail_mailer}, {mail_host}, {mail_addr}
O Milter.macros.envrcpt={rcpt_mailer}, {rcpt_host}, {rcpt_addr}, {greylist}
O Milter.macros.eom={msg_id}

Note that {if_addr} is included on the connect line.

One of these boxes is Fedora Core 1, the other is RedHat Enterprise
AS 3.  Both run sendmail 8.13.3 that was built from scratch:

Version 8.13.3
 Compiled with: DNSMAP LOG MAP_REGEX MATCHGECOS MILTER MIME7TO8 MIME8TO7
		NAMED_BIND NETINET NETUNIX NEWDB PIPELINING SASLv2 SCANF
		STARTTLS USERDB XDEBUG


None of my Solaris boxes, which run essentially the same
Sendmail, exhibit this failure.

So my questions:

1. Is the X-Greylist: header the only thing affected by the
   failure to obtain an {if_addr}?  (If so, I don't deem it
   critical.)

2. Any suggestions about how to proceed to diagnose this?

Thanks in advance,
Rob Stampfli