It's not really a new thing in churches. I've been in churches where this is common even decades ago. We are told in at least 4 places in the Bible to "greet one another with a holy kiss" (Rom 6:16, 1 Cor 16:20, 2 Cor 3:13, 1 Thess 5:26) so I don't think we can say that it's wrong, scriptural speaking. Culturally, well now that's a different thing. In those early times in their culture a kiss, as a token of peace, friendship, and brotherly love, was frequent among all people; and the Christians used it in their public assemblies, as well as in their occasional meetings. Hugs are much the same. In some parts of the world this is still the normal way. In the United States, not so much. We normally use a handshake in place of kissing or hugging unless it is with someone we are close to. So this can make it seem strange in a church until you realize that through Christ, these are actually people who feel very close to you.
PTSD aside, I can't see anything really wrong with it. I just think we need to be sensitive to the reaction of those around us. If a person shys away from this type of thing (as you probably do whether you mean to or not!) we certainly shouldn't force it on them! Friendly greetings of any kind are meant to be something that makes the receiver feel good, not something that makes them cringe!