Mailscanner doing the math wrong?

[Chris Yuzik]

I've just been forwarded some spam that was correctly identified as spam, yet
MailScanner didn't tag it as such. According to the score header, it got a
4.6 (my threshold is 5.0), yet if you manually add everything up, it's really
a 5.37. See below.

Spam: not spam, SpamAssassin (score=4.6, required 5, AWL 0.00, CLICK_BELOW
0.10, DCC_CHECK 4.90, OFFER 0.10, REMOVE_PAGE 0.27)

The only tweaking I've done to the scores is that I've manually changed the
score of DCC_Check to 4.90 in spam.assassin.prefs.conf, like so:

score DCC_CHECK 4.9
dcc_path /usr/local/bin/dccproc

What do I fix and how?

Thanks,
Chris