I logged into my library and I notice things are out of order. The order looks as if it is missing a game and everything has been shifted one place. However my library is large enough I cannot recall every title in it and only detect the issue as I arrange my library into visual / thematic ways. So if something IS out of place I am not sure what it would be. I figure its just some sort of glitch, but it also does not hurt to check and I am not seeing other threads related, so It cannot hurt to ask.

Has there been any games removed from the GOG library this week? I guess for more discussion, once a game is purchased will you still retain access to it through GOG if GOG no longer retains the right to sell it?

You don't happen to own Guacamelee or anything else that's been in a "buy this, get that for free" promo pack? Those don't show due to a glitch; you can contact support for download links if you need.

EDIT: For reference regarding the glitch, in case somebody who isn't aware of it yet stumbles upon this thread:
http://www.gog.com/forum/general/serious_game_shelf_bug/post44

And yes, as blakstar said, games that are removed from the store remain accessible to any user who already owns them. Keeping a local copy is still a good idea, if only because of the possible technical issues such as that pack glitch.

This ^
Guacamelee or Mutant Blobs Attack have both been reported missing from some user's shelves this week. If you had those that may have been what threw off your thematic shelving.

Try this: http://www.gog.com/forum/general/game_shelf_order/post8

Well it took a lot of looking but I can see what occured now. I pulled a game from "hidden" status in order to have a multiple of 5. When moving from hidden to unhidden the unmarked game does not go to the bottom of the "manual" list, but instead restores back to its position on the shelf it held before it was marked as hidden. So not paying attention I found the culprit that got my arrangement all out of whack. So this instance its my own goof.

I do appreciate all the assistance. Marking as solved.

Glad to hear you got it figured out and thanks for sharing the information on the hidden games, didn't know they did that, showing up where they were removed from. Good to know should I want to do a manual sort of my game shelves. I'm still hoping for genre auto sort options, or tabs/shelf labels that I can customize.