In the Joyful Mysteries of the Rosary, we're reminded of the first events of Jesus' life. There's His conception, His mother's visit to Elizabeth & getting to meet His cousin John womb to womb. Then there's His birth, the presentation in the temple & finally (fast forward 12 years), the finding in the Temple.
In the Catholic expression of faith, Mary is seen as a representative of the Church. If we look at the finding symbolically, we could assume that since Jesus arrived with the church, He also leaves with her & goes where she goes. It's been a long journey... The church is tired & looking forward to getting back to the comfort of everyday life. It takes her a while to realize Jesus is strangely absent. No one seems to know anything, so she backtracks. She's feeling a little frantic right now... a little scared. Where IS He?! She goes between feeling guilty & playing the blame game. She looks everywhere- the media, the marketplace- but He's no where to be found. Finally, she goes back to the source of all this- the House of God. She's kind of surprised to find Him there. But Jesus responds to the church by saying "Didn't you know I had to be about my Father's business?". Do we maybe take it for granted that Jesus is with us by default? How long does it take us to discover that our agendas might differ from His at times? Where do we start looking for Him?