Found another gallery-related bug, and this one is more serious than the "not hiding divs properly" bug that I'd encountered before.
It seems that in some cases the password-protected galleries don't show a lock icon but instead show a thumbnail of one of the photos in the gallery!
I think this happens for profiles which haven't yet been upgraded to the new format, as all the profiles I checked for people I know to have switched are working fine. It would be good if some who haven't yet upgraded to the beta profile checked to see if this happens to them, and then upgrade and see if it fixes it. I didn't notice this until after I upgraded my own profile, so I can't test it myself.
Yes, I have reported this bug (and the other one) to MFC, and hopefully they understand how important this is and fix it soon. Even if it's just a thumbnail, many models obviously won't want their password-protected galleries displaying content to people who haven't paid for it.