i don't think its due to the fact that she was embarassed or shy about hugging him.
i think even though sam and gunjan are friends again and talking, it won't be the same as before cuz Gunjan knows that Samrat-Sheena are dating. I guess thats why she backed off quickly from the hug...and did not hug him back (just like in the play rehearsal hug)
rather than the friendly hug, i wish they had done the fist-handshake (whatever its called) that they did in one of the episodes. Its not that I don't wanna see SaJan hug or anything đ. but they should save the hugs for the confession...