Mobile pages occasionally taken over with ads

Every now and then I will click around on GDNet and suddenly get a full page takeover ad like this:

http://d2xdw0i3rxujy9.cloudfront.net/creative/c/4/?rdm=822604&m=1510441410&l=82260415104414047471510441404749473ABAjH0jrV-ZBD07CvShQ6iz9re9Z&platform=android&clickid=15104414047471510441404749473ABAjH0jrV-ZBD07CvShQ6iz9re9Z&adx=1&pubid=1333143972&ctype=3#

I'm not part of the hardcore "all ads are evil" crowd, but a full page ad that disables the back button is some seriously unpleasant stuff.

Only ever happens on GDNet for what that's worth.