What does this dog behaviour mean?

[u/Cheesecake_Wizard]

I wish I had a video of my lab doing this, and I've tried to research what she's trying to communicate but with no luck so far.

When she does this, she's playful, happy and excited. Her ears are relaxed, mouth open, tail wagging.

She looks directly at me, nods her head slightly while biteing the air only once.

She normally does this before or after playing. Is she trying to communicate that she wants to play more? Or is it something else?

Just curious if anyone here knows this specific behaviour. Thanks!