I don't know, but that doesn't seem to be the point. Jesus gave the reason why she was not to touch him... Because he hadn't yet ascended to His Father. That implies that casual touch was either imminent, or that casual touch was a normal course. But in either case, Jesus limited that touch for that moment.
I don’t know either. I know that for some Orthodox Jews, if a woman who is not the wife of a man touches him unannounced, it is considered to remove his cleansed status. As the bridegroom of the Church, He was betrothed to His future bride. There might be a defilement in his status with the touch. Just a thought which I haven’t fully investigated nor have developed the doctrine fully to support it.