India: United We Stand

They have been close since childhood, and well, they are pretty close. She is my gf for last couple of years. Last month, due to a family function, her cousin came down to our city.

And I went to meet her in the morn, I saw they both were sleeping in the same bed!!

Is this common? I mean, gf was pretty normal, she asked to sit on the bed, and we talked. The cousin was still sleeping, and she started teasing him (pulling his ears, pushing him etc), and expected me to join in the 'fun'.

Damn. I felt jealous like anything, but kept a straight face.

I have had very less number of cousins, and have been away from them since childhood.. I dont get this vibes.

Should I get worried, or girls do normally are soooo close to their male cousins? He is a first cousin, (son of her dad's brother).

Edit: I am 28, she is 27. Delhi. Hindu.