No. How do I know that is really someone from the property?

Send them a PM or email to ask them to email you directly? Or contact the GM and ask? Or ask one of the
Starwood Lurkers to verify that they are an official representative of the hotel?
This fee is also waived as part of my corporate rate there. It's never shown up on my bill even when I've booked under public rates, so I would think that would only have been due to my Plat status.