I don't think you did anything wrong, so I wouldn't worry about it. F*ck em, if they want to be a prick about it. I used to loan my tools and shop equipment to friends and family, provided they bring it back when the job is finished. After I had to go get my stuff back every time, I told everyone to get their own. They all got mad at me, but the truth is, if they had done that one simple thing(bring it back) they wouldn't have a problem. I don't feel like I should be a doormat for everyone else, just because they may not like it.