Head twitch after laying

[threeepeat]

I've noticed that two of my falb fee hens sometimes have brief episodes of up and down head twitching or head spasms right after laying. Has anyone noticed before? Is this a known thing? After 2 - 5 minutes, they seem back to normal, 100% fine.

 

[Coturnixxx]

Yes, some of my girls has this behaviour too after laying.