answer: #Person2# gets antsy because #Person2# thinks #Person1# has lost vigilance when praising another guy, but #Person1# trusts the all-right guy.
documents: #Person1#: It seems that you get antsy when you hear I praise another guy.
  #Person2#: I get antsy not because you praise a guy, but because you may be taken for a ride by a guy like him.
  #Person1#: How come you think of him that way?
  #Person2#: Because you seem to have lost your vigilance. You should be on the watch out.
  #Person1#: I have no reason to distrust him. He's never caused any harm.
  #Person2#: Isn't there anything that sounds fishy?
  #Person1#: Nothing smells a rat. I told you that he's an all-right guy.
  #Person2#: All-right guy? All right. Let's talk about something else instead.