My welders know to fill those spots in and grind it back smooth....but to answer your question, I would call it underfill or undercut because it was left due to a welding process....rather than an edge that was thermally cut(torch).
My experience with TPIs have been to just fix it because the TPI has requested it and thank him for pointing that out to you. IOW, It's easier to fix than trying to justify leaving it "as is"....and the TPI gets the feeling that you are trying to run a quality oriented shop vs trying to get something past him. <---(unless it is something really unreasonable that he's asking)