On many (most?) weekdays, priests have the choice of doing the regular readings for the weekday (the ones you were expecting) or the readings for the saint of the day, if the parish or priest has a special devotion to that saint.
There are a few saints whose feasts are “important” enough that celebrating their feast is obligatory (e.g., some of the apostles, certain feasts of the Blessed Virgin Mary, etc.).
Others, like today’s memorial of St. Joseph the Worker, are optional. (His March 19 feast is obligatory, I think.)
Most booklets, in order to save space, don’t print both sets of readings, but often they give the Scripture references to the alternate readings in the fine print. You might want to check yours and look the readings up in your Bible.