Is Obama's decision to label only female reporters as "nice" sexist?

It is always possible that a random calling of reporters could result in only women being called (video here), though if the number of reporters were equally divided between men and women, say 50 reporters, and he then picks 8 women, the odds of that happening are just 0.2%.  But the more bothersome is that he prefaced his decision to call on only women by noting that he was only going to call on reporters who were on the White House's "nice" list.  My question is this: Is it sexist for Obama to only classify female reporters as "nice"?  Does Obama view female reporters as more docile than male reporters?  Does Obama view female reporters as more supportive of Democrats?