Why do I keep getting claims!?!?!

[unmerged(137821)]

Hi I am playing the King of Castille and I have conquered Leon, Barcelone and a few muslim lands. The problem Im having is that I keep getting claims on my Counts and Dukes, I have no idea where they come from, sometimes during wartime and sometimes during peacetime they appear all of the sudden and I understand that having claims on other people is bad for prestige right?
Thanks for your time!

 

[Zsrai]

First off, this isn't EU3 and claims aren't cores; you don't lose prestige for unclaimed counties in CK. The second thing is that I would check your message settings. It sounds like you're gaining claims on your vassals because they are refusing to give you their troops during wars. That can be a symptom of low loyalty, so you might want to look at that before you have mass rebellions too!