[Exim] dot.forward user filter

I have a line in a filter which NEVER equates true:

if $h_subject: matches "pgmr update (uuencoded)"
   then save $home/fname
        finish
endif

HOWEVER if I change the line to:

if $h_subject: contains "pgmr update (uuencoded)"
   then save $home/fname
        finish
endif

THEN it *does* work!

I log "subject" lines in my exim log file, and the Subject that it
logs is indeed exactly what is in my filter above.

Any reason why this is failing?
--
Jim Pazarena    mailto:paz@qcislands.net
                http://www.qcislands.net/paz