"Required SpamAssassin Score" custom function gets called multiple times

[Brent Bloxam]

I've setup a custom function to implement per-user spam scores for 
SpamAssassin

Required SpamAssassin Score = &MyFunc

I have logging inside the function, and see the following in our 
MailScanner log:

Feb  3 14:45:07 mta MailScanner[24111]: MyFunc: email at example.com mark 
score set to 7
Feb  3 14:45:08 mta MailScanner[24111]: MyFunc: email at example.com mark 
score set to 7
Feb  3 14:45:08 mta MailScanner[24111]: MyFunc: email at example.com mark 
score set to 7

Is there a reason it appears to be called 3 times? There are no loops in 
the function that would cause the logging to be erroneously repeated, 
and it's occurring consistently

Thanks for any help.

(PS: Sorry if this message dupes, I realized after sending it previously 
that I hadn't updated my mailman membership to my new email address. I 
imagine mailman would have blocked my previous message)