Annoyed with FMIL

So my FMIL went out and bought her dress like two weeks after we booked our hall. She calls me and tells me she bought her dress and it's navy blue and she knows my mother is supposed to have the first pick so if it's a big deal she'll return it. My mother said whatever and didn't care. My mom finally finds a dress a week ago. I tell FMIL the the color and everything. My mother went a week later returned that dress and got a different one in beige. MY FMIL not knowing this went yesterday returned her dress and got another in the same color. Unbelievable. My mother said she loves her dress and is not returning it which I don't think she should. When FH told his mother she said she loves her dress too and if my mother didn't care about having the same color then she would keep hers too. My mom said that was fine even though I knew she was annoyed but just didn't want to cause problems for me but I'm pissed!!

Do you girls think I'm wrong for being mad?