Girls, If she turns around and smiles/laughs at you?

So in 2 of my classes, there is this girl who normally sits diagonally from me. We have known each other for about 3 months now, and we sometimes talk to each other after lectures. What she has started doing lately though, is turning around to smile or laugh at me whenever I am laughing or sometimes even when I'm not. If she hears me laugh, she turns around, holds eye contact for about 3 seconds, and either smiles or laughs with me. Is this a sign of interest?
Girls, If she turns around and smiles/laughs at you?
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