I’ve been meaning to say thank you so much for the nickname. Oh yeah, glad you like it. It was super easy to come up with. Father Joseph, Father Broseph, Father Bro, Father Brah. Bam! I mean attendance has shot through the roof since you did that.

Okay, so I wanted to talk about this real quick. Right here we see Maggie lick the corner of her lip. This is VERY important to her character and her development. Licking the corner of your lip is a coping mechanism to relieve tension, and why Maggie did this is very telling in the moment. Further into the episode we learn that Maggie was outed and kicked out by her dad. She had written a letter to a girl she liked and in turn the girl had outed her by giving that card to her parents, and so essentially Valentines Day cards had been a huge reason she was outed.
In the beginning of the scene Alex receives a Valentine  s Day card from her mom, and Maggie immediately asks, “ What’s that?” She can obviously tell it is a card of some sort but shows a huge vested interest in what it is right away, knowing that it is Valentines Day. She then goes on to say, “ I always wondered who bought those, let me see this.” and proceeds to grab the card from Alex’s hands. Maggie stating this goes to show that she had not received a Valentines Day card from anyone in her life.
Furthermore, Maggie goes on to read what the card has to say. She reads, “Daughter thank you for being who you are, you will always  be my star.” Maggie never got to experience this before. Her dad kicked her out of his house when she was only 14 years old. She never got to understand what it feels like to have a parents support when she got outed. Her body language and how she reacts reveals a whole lot more though.
When she finishes reading the card the first reaction is to roll her eyes. This is very good portrayal of the character. Maggie isn’t the one to talk about her feeling or even initiate talking about them in the first place She is used to having to push her feelings down and not talk about them, and having to disregard her feelings  as important nonetheless. Then, she goes on to laugh about the card to suppress her feelings even more and try to hide the fact that it reminds her of her past experiences and causes her to be anxious and tense.
One reason why she is anxious is because she is being reminded of how she was outed and how she had lied to Alex to make her coming out experience better. She doesn’t want to initiate that conversation with Alex, so instead she licks the side of her lip. THIS IS SO VERY IMPORTANT!!! This is a very self comforting signal to control the tension and anxiety It is proven that people will touch or lick the lips to remove inner tension, and so since touching her lips would give it away she opts for licking her lip, and since the tension was so great she had to let it escape through that. This is showing that Maggie is doing everything in her power to contain her feelings and not tell Alex quite yet.  
Lastly, I want to point out that when she hands back the card she avoids eye contact and goes back to looking at the paper in front of her and takes and brings her left legs up to her chest. Maggie bringing her leg back up to her chest and signify comfort She brings her foot up to show comfort by having her leg be close as possible to her chest to comfort her and build a direct wall between her and Alex, it can also be Maggie returning to how she was sitting before she had seen the card, but that can be up to your interpretation.
Anyways, that was my dissection of that scene and I hope you can all agree with me on the many points I have made that Maggie’s was trying to hide her true feelings from Alex in that scene through subtle body language such as licking the edge of her lips.