"Just a thought...you would be able to see your own private trees on Mundia, and anyone you invited to your trees would be able to see them as well. Could that possibly be what's happening?"
Short answer, NO.
My ancestry private tree showed up in a google search which included all the documents & photos. Obviously Mundia had the complete tree but if a basic google search produced my PRIVATE tree, Mundia has big problems protecting our privacy.