Under the chin tattoo for women (meaning)....

I was out today for a beer and the female bartender had a tat under her chin. First time I had seen this and I asked her about it and she showed me. Then she came to my table later and I told the person I was with (also female) about it. She said it is a newish trend amongst lesbians so the female performing cunnilingus on her can look up and see it. Am I the only person who didn't know this or is it a new trend? The female bartender with the under chin tat was in her early 20s, I'd guess.