Been playing for about five years and this is the first time I've run into this, so "bug." Wayshrined into Windhelm today and heard the drunk Nords singing "Mead, Mead, Mead" for the first time. Considering Pact main (and alt) and uncounted pickpocketing trips to Windhelm (and Uncle Sheo's holiday), either a bug got fixed or one got introduced. Not sure which, but pretty cool on first encounter.