Yes, the football team may have started this in the late '50s as a sign to each other on the sidelines as was mentioned previously, and it caught on to a larger degree sometime in the '70s amongst the general student population.
However, the Mustang Band began using this sign in the late '50s. Irving Driebrodt, the band director who introduced the all male band to the university in '58, would give the victory sign to the band whenever he wanted them to play "Peruna." So, for the Mustang Band, at least, we've used the pony ears since that time.
