Since the spontanteous movements started to occur there's been a lot of mudras and asans that I'd love to be able to explain, but this one is really special and easy to describe, so I'll share it here:
Sometimes (usually after lying in corpse pose after meditation) I feel strong urge to stick my tongue as far as I can down to my right cheek, than to the left one. After that I stick the tongue out and down in the front of my face so that it touches the teeth and have to move it left and right against them, while pressing strongly downwards. If I'd repeat it many times it would result in cutting the frenum by the teeth! Has anyone experienced it? Do you think that it's an instinct of cutting the frenum? I'm pretty sure that's the reason, based on the internal phenomena that I feel (ecstatic 'reward' for pressing the tongue down and moving fast against the teeth), but I'd like to hear from you about it.
That looks like some form of talabya kriya at least the part of going down and pressing downwards is very similar to talabya. It s a technique that is usually given in some Kriya yoga initiation.
Now the part of moving left to right sounds very interesting.