‘And when she had said this, she went away, and called Mary, her sister, secretly, saying, “The Master has come and calls for you”.'
Having made her plea she moved away leaving it in His hands. It would not have seemed seemly for her as a woman to remain with Jesus. And so her practical thoughts turned to her sister. Did Mary know that Jesus was here? She went to her without any fuss and told her, ‘the Teacher is here and is calling for you'. This description ‘Teacher' contrasts with ‘the Lord' in v. 26. That had come out in her awe at Jesus' declaration and revelation of Himself, ‘the Teacher' was her normal way of thinking of Jesus.
‘Calling for you'. Jesus still waited outside the village. This was the time for privacy and He wanted the sisters to be able to see Him alone. Note how it indicates that we have not been party to the whole conversation.