In today's Gospel, Jesus answers those who kept coming to him looking for signs. Short answer? No. Because the kind of sign Jesus brings isn't the kind that our eyes can see: it is a sign for our ears. We don't perceive this sign with our seeing, but with our hearing, the way the Queen of the South heard Solomon's wisdom, and the people of Nineveh (featured in last week's readings) listened to Jonah.
The first reading corroborates this in the way that Paul, in the very first words of his massive letter to the Romans, keeps repeating "hearing" language: "Paul, called to be an apostle... the gospel [good news/message] of God which he promised... the obedience [root word is "to hear"] of faith... called to belong to Jesus... called to be holy."
The Bible seems to hint at what Thomas Aquinas said about the Eucharist: "Sight, touch and taste in Thee are all deceived; the ear alone most safely is believed." Paul simply ends up saying, "Faith comes from hearing."
So keep your ears open for that sign!