I've had this happen multiple times now. I'll que for a random dungeon, get a notification that I've found a group, and then someone disband s the group before I even have a chance to travel to the instance. It's really annoying because I don't have a ton of time to play and then I have to wait another 15 minutes before I can que again.
My suggestion is this: if you que for a dungeon and the group is disbanded by someone other than yourself, then the 15 minute lockout should be reset. I understand the reason for the 15 min lockout, and support it. But there should be some mechanic that will allow me to re-que if I didn't even make the jump to the instance.