Carter's 3 Months one-piece zipper pajamas winter pink fair isle reindeer flawed

This cute zip-up one-piece is made by Carter's for babies 0-3 months. The pattern is a reindeer winter fair isle design in dark pink. PLEASE NOTE: (See photos) As I was photographing this, I noticed that the button had caused discoloring. It happened between storage and the wash. Someone may know what to use for it to easily wash out. I'm assuming rust from the button. I marked it down from $12 to $7 due to this :( Still cute and very functional tho!! Weight: 3 oz