Well, this is possible, I think, because the souls in Purgatory belong to the Church of the Mystical Body of Christ, and they are called the suffering Church. All three parts of the Church, the triumphant Church, which is the saints in heaven, we on earth which are the militant Church, and the suffering Church in Purgatory, are in communion. They can sometimes receive signs from the saints in heaven and the souls in Purgatory, with the permission of God, who can also manifest in different ways to ask for prayers or spiritual help. This is, in principle, possible in every case. It must, of course, be examined to be sure that this is probably a sign of a soul asking for help. Therefore, when such signs occur, this person should pray more for the departed soul and have masses celebrated for them.