Would this bother you? I'm not sure what to do...

If it was something I REALLY wanted and knew it was authentic, it wouldn't really bother me. I keep most of my authenticity cards in an envelope in my desk, so it wouldn't make much of a difference to me.
 
I bought a DS flap from ebay, it was authentic but because it was ex-display there was no auth card or care booklet and a few minor scatches on the CC plate at the front of the bag. But the seller gave me a good price and the bag was authenticated on the forum so it hasn't bothered me at all. The hardware would have been scratched by myself eventually anyway.
 
As long as I knew it was authentic, and that I would never want to resell it (so I woudlnt' lose too much money on it) I'd buy it. I've purchased runway shoes on Ebay and they take the black mark across the name, at first it bothered med, but how many people really see it? And if I can save over 1/2 the cost....that means I can buy something else too I love! Its a win-win.
 
I remember seeing a beautiful bag on ebay while perusing through the other day; it had the X through the inside label and I wondered why the seller did that? I can't for the life of me remember which bag it was (although it reeled me in enough to click on the auction and admire the photos!) but if you really love it you should buy it as long as you're certain you won't turn around and resell it (cause the next buyer may have the same reservations you do).

Let us know what you decide and share pics with us!
 
Buy it, use it, love it and forget about the other stuff. I buy my bags to use and they are going to get little marks even though I am pretty careful. After a month or so, you won't even think about it.
 
Well I tried to negotiate with the seller a larger discount than the 1/3 but it didn't fly. If it were half price, I think I could live with the mark but not sure about it at 1/3 off.