When is kissing an ex in the mouth just wrong?

During a recent gathering, my husband was doing his usual greet to everyone, which includes a handshake for some, hug for others, but on this day I walked up behind him to speak to someone and found him bending down to reach the lips of an "ex" girlfriend and watched while he planted a kiss on her lips. He had time to think of these actions since she was seated and he was standing. I blame him, he initiated the "greeting". WhenI confronted him with this it seems it isn't the first time and he see nothing wrong with it. I pointed out if nothing else she is recovering from a medical concern and should be careful of contact in that way, a nice way of saying hey you screw up! His appology is lame at the very least, he thinks it's funny and no big deal. Well for our marriage of 30+ years it's a big deal. I have always tried to be nice to this woman because I work with her in our organization and due to her illness. It hurts to think my husband could have thoughts of the past or be so stupid not to realize how his actions looked. Did I mention the table of old women in shock at what they saw. Am I embarrased, over reacting, or just stupid.