What does spikey head feathers on a budgie indicate?

My mother's parakeet is four years old, and appears for all intents and purposes healthy and happy. A huge cage, lots of sun, good appetite, energetic and peppy. Lately, however, she has developed one odd symptom--a few randomly placed spikey head feathers scattered among the normal feathers. At first, we thought this was perhaps a moulting stage, but now this has been going on for weeks and weeks and seems far beyond any other moulting signs. There really seems to be no other symptoms. I know she has a habit of rubbing her head really long and hard on this natural twig my mom put in her cage; she seems to love it. Could that be affecting those feathers? This really seems to be something with how the feathers are actually growing in. I remember reading in a bird book years ago what spikey head feathers represents, but I can't remember and I can't seem to find any info anywhere else on the subject. Advice appreciated!
The budgie is molting. When birds molt feathers gradually fall out and are replaced. The new feathers growing in are covered in a keratin sheath and are "spiky." There is also a blood supply in this feather. As the feather grows the sheath wears off or is preened off by the bird or its mate and the blood vessel recedes. I take it your budgie is housed alone. If another bird was in the cage they would preen each other on the one place a bird cannot preen itself - its head. Some owners are able to gently scrape these sheaths off with their fingernails with tame birds. This is what you are seeing.
The spikes are new feathers. They come in with a hard capsule like covering. My conure got them regularly. The head rubbing is to try to get the capsule to come off and I wondered if they itched. My conure would carefully chew them off where he could reach. I gently crunched them off on his head sometimes and the feathers came in fine.

You may find the answers here.good luck!
The whole moulting process can take weeks,especially if the moult was severe. That said, there is something else...Polyfollicles... which is the growth of multiple feather shafts from one follicle. It may cause no problems or may be associated with chronic inflamation in feathers and skin. An itchy pollifelliculitis has been seen in lovebirds and budgies. This condition is thought to be caused by a virus. If you are certain its nothing to do with a moult,I would advise a visit to a vet. Are her droppings normal?
You also mention the bird has plenty of sun? Never place a bird in full sun.
Your seeing the new feathers coming in..they are enclosed in a thin waxy like shaft.
If your bird is a single bird with no mate..you'll have to help her scrape the shaft gently with your fingernail..the shaft coating will come off easily.
She can't reach all the areas of her body so thats where you come in.
The new feathers will itch and make the bird uncomfortable until all have been de-coated.

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