Oh my the bag does seemto be authentic, but t sure does look like someone drew on the eyes of the blossom. If I were you I would get a refund from the ebay seller, and use that money to but a different lv bag that does not have the default.
A few years ago I purchased an authentic CB retro from a seller, and when I recieved it i notices that the blossoms on the flap of the bag were a darker colour pink to the blossoms on the bottom part of the bag. It must have been due to the different cuts in fabric. It was totally authentic but just had this default,and I could notice it so much that I decided that I did not want the bag.Therefore I actually sold it and another boardie brought it from me because she did not mind the defect. And it actually had tons and tond of blossoms on it.
Here is a pic of the diffent coloured blossoms(see how the blossomson the flap are pinkeir than the colour it should be on the rest of the bag).
Kimmy your CB Retro was lovely!