yup, did the same. Had mine vertical for about a year. did not move it while the disc was spinning, however walked past it a few times while it was sat on a floating floor that naturally gives a bit. That was all it took and my Mass effect disc was done.
Since then it has been horizontal and has sat on a stand. I have not moved it either. I will happy chuck the PS3 in the back of the car when I go a'visiting, but not the 360. Better safe than sorry.
Your console should be fine and MS, I think, will replace the discs for a price. They did when I did-in my disc in about a year and a half ago (or when ever ME came out).