Nice catch!
Looks like the /opt/zimbra/conf/dspam.conf wasn't updated.
Update the lines:
Home /opt/zimbra/dspam-3.6.2/var/dspam
StorageDriver /opt/zimbra/dspam-3.6.2/lib/libhash_drv.so
to point to
Home /opt/zimbra/dspam-3.8.0/var/dspam
StorageDriver /opt/zimbra/dspam-3.8.0/lib/libhash_drv.so
Bug 23216 - dspam.conf refers to previous version