I will admit that its current route in the HB is correct based on signage in GSV in 2008.
This also agrees with your statement.
RMSSSEG_State_Roads shapefiles show US 62 B on Irvine, connecting just inside the state line. I don't see signage at the western beginning, but do at the
Irvine <-> State turn.
The E-W leg, currently in the HB as
PA US62BusSha US62_S IrvAve_S, is listed as US 62T. Not signed as a truck route as such, but this explains its ample TO banners.