The other day I was working on a map and after i saved and quit I went and played customs with some friends. Later on when I went back to work on my map some more some of the objects I had placed were not where I had placed them. It was like someone had moved them and I nknow that nobody had because I hadn't got off the x-box. Anybody else ever have this problem.
This has happened to me before. Depending on which map you are on, the objects may slide by themselves to a different area. For example, I built a race track on Sandtrap, and when I came to play it on custom games, some of the objects I placed down as barriers had drifted to a different area. However, if you built the map on one of the newer maps (Foundry, Rat's Nest, Standoff), and were using non-moveable objects (Double Box, Single Box, Bridge, etc.), then I am not sure what happened. Just be sure that everything is where you want it to be saved when you go to save it, and that shouldn't happen.
Lag can revert your placement to a previous saved state, so it's possible this happened and you saved soon afterwards. Could be your reason.
No, that's very unlikely. It usually happens when someone enters or leaves the game. Alternatively if you are using a glitched canvas it can turn up some weird problems like this. You may remember my objects disappearing randomly in recent forges which I believe was due to this reason.