Matthew 26:11

“For you have the poor always with you, but me you do not always have,”

He reminded them that this was a special time. They would always have the poor with them, but He would not be with them for much longer. So someone who had recognised this, and had wanted to demonstrate her love, was not to be criticised. Let them also take note that soon He would be gone, and then they would be unable any longer to physically reveal their love. There are times when lesser things must give way to the greater.