They werent expecting the pushback from the Birther issue or at least not so soon. Am glad it’s coming from outside the campaign. The nail for the coffin of the issue is the Phillip Berg legal papers. No doubt of the documentation Also no doubt of Bergs support of HRC
I think they expected pushback, but of a different sort. It didn't matter what Trump said, they were going to ream him for his interest in and questioning of Obama's credentials, between 2008 and 2014. Totally not a campaign issue, brought up on the initiative of the press.
The only technical error in Trump's response is assigning the origin specifically to Hillary. Smart move, to pin the issue on her, because by digging into the "false claim," the press has to report that it was Democrats, and they had to be Democrats who were advancing Hillary at Obama's expense, who brought it up in the first place.
Funny too, the press has reported Trump's stating the allegation that the digital image produced by Obama is a photoshop, forgery. Some people have not heard that allegation before, the press downplayed it.
I expect Hillary to keep beating the drum though. She has to. Trump is making inroads with his policy prescription and affection for assisting poor communities, which have a higher concentration of African Americans. She has to revers that trend, and "racist bigot" is the only card she and her supporters in the race hustling industry have. The commentators and hosts on the networks are predominantly race hustlers too, so it will be difficult for them to let this go.