Yes....it is normal and Yes.....some have stronger hands than others. I've never found them to be a problem.
The only thing that has smoothed and lightened my decockers is an action job or tigger job or spring kit. This makes them very nice!!! I wasn't trying to do this to the decocker but it happens to be a side effect after doing these. Once you understand how the decocker functions, you will know why.