The music licensing firms will try to collect from any group performing music that comes to their attention. Since 100 per cent of their collections from live performances goes to the agencies they are especially diligent in this particular area. If you pay up or go out of business they are happy. If you can present a playlist verifying that the music performed is in public domain, they most likely will leave you alone. They do not pursue any case they are not likely to win. Been there.