SPF_PASS doesn't trigered

[Nikolay Shopik]

I have domain hosted at google apps, and my domain have recomended by 
google txt record "v=spf1 include:_spf.google.com ~all". So far when I 
receive mail from this domain spamassassin doesn't trigger rule SPF_PASS 
nor SPF_SOFTFAIL, is this normal?
I'm running 3.3.1 version