Mine fell from vertical position too, it was off. Happened at the release day but works perfectly now so you shouldn't be worried.
if it falls its your fault. If you read the manual and put the glass stand on it, it has a very very low chance of falling. unless someone drop kicks it.
Wii on 25/12/06 - Ps3 on 10/07/07
Brawl: 1976-9887-4438 Bowser Player