Allow me to explain what you probably witnessed.
At my father’s old parish, there is a custom in my dad’s old Parish that was begun three pastors ago. Every Wednesday at the 5:30PM Mass (except during Lent and Holy Days of Obligation), they have a custom that just prior to the final blessing, the priest leads the people in the Novena to Our Lady of the Miraculous Medal. There are several prayers and then, after that, the priest imparts the final blessing to the faithful.
Then, they line up, similar to those who are going to receive Holy Communion and then he touches their foreheads with a first-class relic of St. Catherine Lavoure. While all of this is going on, elderly women are singing a hymn to the Blessed Mother in Spanish.
You didn’t, by any chance, go to that particular Mass in my fair city, did you? What you described is exactly what happens in this parish, and yes, the relic in question does belong to St. Catherine.
What you described is eerily similar to what is happening at this particular parish down here.