David Letterman is catching some backlash on social media over a resurfaced interview with Lindsay Lohan in which he seemingly mocked her for going to rehab. The interview was from a 2013 episode of "The Late Show" in which the star was on hand to talk about her new movie and TV project ahead of a very public stint in rehab.The troubled star had been in and out of treatment since 2007 amid a flurry of public gaffes and addiction issues.