Backup set growth

Hi,

I have a differential job. yesterday I found out that it has been about 30 gb growth on the tape incomper with a day ago, I was sure that there was nothing has been change on the folder that differential job create a backup of, so after some reserach findout the only thing that has been change was that I did add one user to securtiy group of that folder.

my question is,

can we configure the BE to not backup the files just becuse the security of a folder has been change? or this will heppens regardles of which attribute of a folder  has been changed?

Thanks