Customs Agents at Logan Airport in Boston are using a new repeater, 170.7750 NAC $319, unknown input but possibly 163.2500 NAC $301. There's been talk of meeting arriving aircraft, Passport Control, Agriculture etc.
It appears Customs is gearing up most airports again. They recently did extensive drive testing at PHL for their 169.55 repeater. Similar activity to yours has been monitored since around Thanksgiving.