Three things huddle below the surface of this event.

First of all is what made the Lady Mary pointedly call her Son’s attention to the failure of wine.  She knew that He had not yet used His powers, so insisting now means that she felt that He was in some manner connected with the failure.

Maybe it had to do with the crowd of followers He has brought with him—already a lot more than the invited guests. They drank a lot of wine. Then Her Son has contributed to the failure of wine; He’s responsible for a solution and the Lady Mary calls His attention to it.

Then, second, we learn here that as He began His public ministry, He was careful not to seem to be a wonder-worker. He wanted to be careful to make His proclamation clear and broadcast–Repent and believe the Good News–before He did any marvels to back up His claim to more than ordinary powers. Jesus Christ came as a teacher. His miracles were after that.  

Then, third, He had brought that intention to the Cana feast, and when the Lady Mary told Him–They have no wine—she seems to have been doing several things. First, indicating that Jesus had contributed to the unplanned shortage of wine. Second, that He has shortened His own time frame by bringing so many mouths to this wedding feast. And third, whether Jesus felt it was time to do a marvel or not—it was time.

So He listened to His mother. Well, maybe a little over-enthusiastically. Fill the water jars. Take out the wine. It is more than plenty. It is the best.  And then, the bridegroom was a bit embarrassed for having kept the best to last.   And did the Lady Mary stare at Him?  Was He teasing her? Or may be this was just His way of making certain that the Wedding Feast at Cana turned out to be really memorable for all the invited. And a few others, too.