I've seen a mother cat that had just given birth. In the first few hours, she was constantly licking her kittens all over, including their genital areas. This licking serves multiple purposes. It not only cleans the kittens but also helps in the bonding process between the mother and her babies. It's an essential part of the early care that mother cats provide to their kittens.
There could be a lot of nervousness. It's a new experience for both, so they might be worried about how the other will react. Also, there's excitement as they are exploring a new level of their relationship.
Let's say there are two young lesbians. They've been friends for a while but now their relationship is evolving. They are in a quiet room, candles lit, creating a very romantic atmosphere. One girl gently touches the other's face and then, slowly and tentatively, gives a lick on her cheek as a way to start this new and exciting journey of physical exploration. It's a very delicate and meaningful start to their new - found intimacy.
Well, once I was helping at an animal shelter. There was a shy little kitten. When I first had to check if she had any sores in that area, it was a gentle process. I had to be really careful as she was scared. I used a soft swab to do a quick check. It was a new experience for me in terms of handling such a young and timid cat in this way.