The calendar of the Roman Catholic Church includes feast days, each celebrating the life of a different saint (or in this case, angel.) The liturgy (prayers, readings etc) of the day is appropriate to the saint in question. The Feast of St Raphael is 24th October. The Gospel reading for that day is John 5 v. 1-4, which describes a pool that intermittently becomes turbulent when disturbed by an 'angel', the turbulence producing healing powers in the water. The story of Tobias also features prominently in the liturgy of that day.
Michaelmas, the feast of St Michael and All Angels, is 29 September. The Monsignore obviously thinks it would be a pity if the two were combined.