Thats what happened to me. http://www.bladeforums.com/forums/showthread.php/1143331-Tip-Up-Disaster-(graphic-content)
Only once though. I'm a quick learner ;-)
Dang, that could have been ugly! Haha I hope I don't have that problem as I usually carry my folder in the right-hand corner of my front, right pocket so hopefully that should keep the blade tucked in nicely. I haven't had any problems with any of my others there, and I've done some pretty crazy shit while they were in my pocket. Haha