This is most common with the henchmen who have been around for a while. Henchman should feel free to grow their personal collection, of course. And there is are other perks as well.
Henchman who want to help out at Gen Con have, in years past (including this year), gotten an invite to our "after party." Which is a fancy way for saying "The Wyrd Bosses take us all to Hard Rock Cafe" and we get to hang, eat burgers, bang down some brews, and tell cool stories. It's a ton of fun.