This isn't really uncommon if you touch a fan blade. Had this happen with a sunon and yate loon before. Mind you I wasn't the one that did it. This is one of those things I don't understand. If you can see what you're doing you shouldn't hit anything unless you're having a sugar crash. If you can't see what you're doing get a flashlight. Never done this and I pop my side panel off a lot. Even when I'm checking to isolate a noise I know you stop a fan from friction on the hub, not the blades.
Just be more careful and problem solved.