Kristy My WM is a stupid one that doesnt have a lint filter, so I get this on absolutely everything. Microfleece (the fabric used on the outer of the basix and the inner of the coutures and new basix) does pill and fluff regularly for me, but I tend to quickly brush it off or just dont worry about it. It does not affect the functionality of the nappies. The newer ones I am finding better, the Microfleece is smoother.

The older style Basix have flannelette inners. The boosters are not sewn in on the snap version on the older ones whereas they are on the newer ones. It is possible that is they are the older style it could be coming from the inner and spreading to the outer and attaching to the MF.

Throwing them in the dryer for 1 or 2 washes may also help. The dryer always finds more lint than the washing machine, and the static in the dryer tends to help it not to stick to the clothes.

I am getting some pilling on the outer of some of my minky coutures, but it is really easy to remove with a lint shaver.