does the X-Bogosity line mess up spamicity calculations?

[Trevor Smith]

For now I have not been using -u when I run bogofilter (while I manually 
observe if things are working). After I confirm that spam and ham are 
separated as they should be, I train bogofilter with new messages that have 
come in. But these messages already have an X-Bogosity line in them. Is this 
undesirable? Does it matter at all? Does it matter a bit, but not enough to 
really matter?