You can look up the current classification of any site via the 'Content Filter Lookup' functionality via the Policies > Categories tab.

If you believe a classification to be incorrect, the best practice is to submit if for reclassification via the 'Content Filter Feedback' section on the same page. Reclassification can take up to 3 working days to be reflected in your database. In the meantime if you wish you can whitelist or blacklist the site, via the Filtering > Domains tab.