My ball python (Nagini) does this all the time. I only notice it when she's around my neck. I was concerned about it so I checked the forums, thanks to everyone here I believe it probably is stuck shed in her nose or substrate or something.

She pokes her head out of her hide when I walk by her cage to let me know she wants out; I hold her for about 12 hours a week while watching TV/movies.

I like to think of the breathing as a sigh of affection, or fangirling .