The Sign of Peace... in the Gospels?

Earlier this week I was reading Jesus' instructions to the Twelve prior to sending them out to the villages he planned to visit. I found myself wondering about this particular verse, "And whatever town or village you enter, find out who is worthy in it, and stay with him until you depart. As you enter the house, salute it. And if the house is worthy, let your peace come upon it; but if it is not worthy, let your peace return to you" (Mt. 10:11-13). What exactly did the Lord mean, "let your peace come upon it...but if it is not worthy let your peace return to you?" I'm not sure, nor can I find a satisfying answer in the commentaries I have consulted. Perhaps peace, in this context, simply means fellowship, friendship; when we extend charity to others, and it is not reciprocated, our souls are not depleted in any way. I still feel like there is something more to be learned here.

Regardless, this verse returned to my mind at today's Mass during the Sign of Peace. At Mass we unite ourselves to the prayer and offering of the Lord Jesus. We turn to each other as members, cells, of our Lord's Body and, in His name, say "Peace be with you." We are like the Apostles in the gospel, speaking peace upon the house that the Lord will enter in Holy Communion. And just after the sign of peace we petition the Lamb of God to send us His mercy and peace, finally kneeling and confessing, "Lord, I am not worthy that you should enter under my roof; but only say the word and my soul shall be healed."

The question then becomes, "Will I allow the Lord's peace, His friendship, to remain upon this house - upon me? Or will I squander this gift He has made to me of Himself?" There seem to be so many ways to do so - sins of speech, neglecting Him in my thoughts, etc. I just offered a prayer for all who read this, a prayer that you cooperate with His grace and continue to live in His peace. I would be grateful if you did the same for me! 

And he came and preached peace to you who were far off and peace to those who were near; for through him we both have access in one Spirit to the Father. So then you are no longer strangers and sojourners, but you are fellow citizens with the saints and members of the household of God, built upon the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone, in whom the whole structure is joined together and grows into a holy temple in the Lord; in whom you also are built into it for a dwelling place of God in the Spirit.   Ephesians 2:17-22