How the sign of peace is shown is not scripted or formatted. I never shake hands with my wife, I kiss her…but, neither do I ever kiss the lady sitting in the row in front or behind me, I simply shake her hand
Some people just do not like to shake hands, and that is hardly an indication that they are not wishing someone peace…in the winter flu season, I am very picky about who I shake hands with at the sign of peace if I am in a crowd of wheezing, coughing, sneezing, folks…it can be done without offending anyone, and doesn’t mean I am rejecting their friendship.
When you visit other countries, or even geographic areas within the same country, you see different customs for sharing the sign of peace.
The most charming I saw was a Mass in Iraq. The way it was conducted was the priest shook hands with the alter servers. The alter servers went down the isle, shaking hands with the person setting on the end of the pew. That person turned and shook hands with the person next to him, and it continued down the pew…Kinda like a Wave at a footboall game.
We often don’t know when people pray for us, because we don’t see it. I imagine the same is true of their offers of peace to us. Just because there is not a physical gesture, does not mean they are not sharing peace with us.