Hollister Sizes?

Okay, so I was walking around the Hollister store yesterday (I was very confused, store was like a maze, compared to Abercrombie) and saw this sweater, and it was "Betty's" size which I didn't know, but I'm a boy. So I took it to the cashier, he didn't say anything (guess he thought it was a preasent), and handed me the fancy Hollister reciept, I got in the car, and saw that the reciept said "Betty's Core Fleece" but I was already half way home, I tried it on, it was a perfect fit, but I'm not sure if anybody will notice it's a girls size. What should I do?