[tbob]

Most of the time something like this happens, it is family-related. The grandson of Frank Miller has just about cornered the market on his Obaks and Zeenut cards. Ditto the families of Lindsey and Fullerton in the 1911 Zeenut set. To a lesser extent a relative of Jack Coombs was about 5-6 years ago buying up as many of Coombs' E98 cards as possible but I don't think he is still doing this.
For a while the T206 Burch batting and Lindaman, especially in higher grade, were being scooped up and had high price tags for commons but these two cards seem to have come back to earth and are accessible again.