Last year, Pyramid put out a commemorative black nylon tapewound set, the
648/RT ("Rooftop '69"), with long yellow silks so that they look like the Rotosounds Tru Bass tapes that Paul McCartney actually used:
Pyramid Strings Unveil New Short Scale String Sets
Pyramid 648 Rooftop
(I've seen conflicting reports on the silks of regular Pyramid tapes: some say red, some say orange, some green like the flats.)
So it's a mild gimmick on their part.
Of course, in Bunny's case it's statistically improbable these are Pyramids (they'd have to be recent, and about 33.25" from ball-end to silk - if they aren't, that rules them out automatically): they're likely to be Roto 88 all right.