I've had this happen to me, I gave my SIL expensiveish cushions that were mine but I changed styles and she loved them so I passed them along. A few months later she'd listed them for sale on a FB site. I personally was offended that she was making money off them, I felt she should have either given them back or passed them onto another family member as others also loved them.
See I see that as different. And definitely not very nice manners.