What you are seeing is normal molting. Nothing to be concerned about.
Just because you don't see pin feathers on their heads doesn't mean they aren't molting.
I have seven budgies downstairs and I'm vacuuming up feathers twice a day right now. (To say nothing of the two budgies and three lovebirds that are upstairs!)
Everybirdie in my house is molting -- it's that time of year.