I imagine that the MA police went to pick him up, and they did so based on a determination that he was not in custody for the NH warrant.
FUGITIVE FROM JUSTICE. [federal] Any person who has fled from any State to avoid prosecution for a crime or to avoid giving testimony in any criminal proceeding. 18 U.S.C. One who, having committed a crime within a jurisdiction, goes into another in order to evade the law and avoid its punishment.
If what you say were true he would be facing an extradition hearing. However, you could be right and this fugitive from justice could be on an unrelated issue altogether.