Since the incident that led to the meeting of Earth and Equestria, Luna, Celestia, Twilight and just about every other high-ranking official in Canterlot have been scrambling to work out how to introduce humans and their culture to Equestrians. Thus far, human interaction with ponykind has been kept deliberately sparse outside inter-governmental talks. Human and pony civilians are advised to keep contact to a minimum until the details are worked out.
So when Twilight takes a break from her duties to clear her head, she is taken rather aback by the sudden presence of a human record store in an alley. This deserves investigation!