it's a fake. and a not very good one at that.
and gosh, where to start - the lining is the wrong colour, the leather plaque below the zip is the wrong shape, the pull on the zipper is wrong and most importantly, the leather used for that particular style isn't the smooth.
remember, if it seems to be too good to be true, it usually is.
btw,
NET-A-PORTER always have really good pictures of Phillip Lim bags, they always show a decent shot of the lining, zip and leather plaque, so it's always best to check their pics first.