Yeah who knows…but it would be a little strange to COR an hourly METAR and leave the -SN in the ob if it was really PL. Vis dropped to 1.5sm too and the previous SPECI was +1C. Lots of legit snow obs in NE MA too from the salt nuclei. I think CoastalWx reported some RASN as well.
KBOS 291954Z COR 04015KT 1 1/2SM -SN BR BKN010 OVC015 02/00 A3015 RMK AO2 TWR VIS 2 SLP210 RAB04E18SNB44 P0000 T00170000