Also posted this observation to BugGuide: https://bugguide.net/node/view/2111532

See https://bugguide.net/node/view/601838 and in particular:

"native to Europe (widespread), adventive in NA (NS-ON & NH-NY; BC)(1)(BG data)"

full text of the citation on that page: http://www.chebucto.ns.ca/environment/NHR/PDF/Introduced_Maritime_Staphs.pdf

Introduced Staphylinidae (Coleoptera) in the Maritime Provinces of Canada
By Majka C.G., Klimaszewski J.
The Canadian Entomologist 140: 48-72, 2008