I have an uncle who always tries to embarass every woman in the family by kissing them all over their face and hugging them for a ridiculously long time - simply because he knows we hate it. When we were younger he was worse.... he did it to everyone - me, my mum, my cousins, his daughter - because he's a joker and he knows people will laugh!
But if this step dad is trying to do this on the sly and with only the two of u in the room then i;d certainly be worried. Tell your hubby ur very serious and dont feel comfortable. Maybe he could have a word with him.