I recently purchased two Builder's Bundles on-site, and when checking my gifts waiting to be redeemed, I noticed that some had vanished, including the gear set from the Dino Bundle, which is gone now. I assume this is because I also had some other gifts waiting before, and they hit a space limit, given that it filled up at 10 pages exactly. I've sent a support email already, but I wanted to be sure that this was resolved, especially since there is no warning provided about this. I'm posting in the hopes that eventually a warning will be added to bundle purchases, or code redemption, and that my missing items will be returned.
So I guess I panicked too soon, because after I claimed some gifts and logged in and out, the rest reappeared. A warning that you can only have so many pages of gifts would be nice, but it's fine now.