Just as we can empathize with others--as when we flinch if we see somebody get injured, and we may even feel pain though we are not the one who was hurt--so we can imagine things that we haven't done yet. Did you ever see someone joking around by pretending to kiss their own hand by pressing their lips to it, or to hug their own body? We know what it feels like to kiss in a platonic way, even to kiss a pet. We know we have a desire to kiss, once we reach a certain age. We see it in movies or we may even observe others kissing in real life. It does not take much to imagine the physical sensation and the enjoyment of it. When you really do it, it may be different from what you imagined, but it can come pretty close. So there is nothing strange about this at all.
Dreaming vividly about things you have never done--let's say galloping across the plains on a wild horse--often makes people feel as if they are dreaming about another lifetime. The mind is amazingly creative.