What you're describing is friction as you drag the expander button through the neck of your cases.This is normal.
I wouldn't touch the expander until you have tried this!
With a neck brush of the correct diameter,a little bit larger than bullet diameter,dip the brush in powdered GRAPHITE,remove any excess,and run it into each case before re-sizing.You will know when you need to add more graphite when the cases begin to drag on the expander again.
This method will give you better cocentricity because the expander won't drag heavier on one side more than the other,this is what the dragging is.
Thsi will also make your necks stretch less,when the expander drags one side of the neck,it pulls that brass with it,making it longer on one side only.You can visually check this.