Oblivion has been playing very well on my new computer. Earlier tonight, though, I encountered something odd. Across one end of the IC Market District was a "wall", or veil, of orange, and a few moments later, on the upper floor of the Merchant's Inn, one end of the corridor was filled by another "wall" of green or black. These walls did not inhibit movement--you could walk through them--or affect the game in any way I could see. My character slept at the inn; in the morning both walls had vanished.

Does anyone have an idea what kind of glitch this was? Should I be worried that it portends some later serious problem? I have never seen this oddity before.