spf test not always running?

==== Required information ====
- iRedMail version: 0.8.6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): PGSQL
- Linux/BSD distribution name and version: RHEL6/64
====

It almost looks like Spamassassin is not always runing the SPF test.

For example, here's one such email:

X-Spam-Score: -2.155                                                                                     
X-Spam-Level:                                                                                           
X-Spam-Status: No, score=-2.155 tagged_above=-9999 required=6.2                                         
        tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RDNS_NONE=0.793,                                   
        UNRESOLVED_TEMPLATE=1.252] autolearn=ham                   

Note no SPF in that one.

Here's another:
X-Spam-Status: No, score=-13.407 tagged_above=-9999 required=6.2                                         
        tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RDNS_NONE=0.793,                                   
        SPF_PASS=-10] autolearn=ham

There *is* SPF in that one.

Any thoughts?

thanks.