Yes, it was because of an injury in universe (I think it was. I have no intention of ever rereading preDC notRID). Bee's not old enough to need a cane simply because his body starting to give out on him. However, from a story telling point of view, the association people make between a cane and old age is used so Bee's cane represents how he stopped being a little kid, and became the Autobot's leader. Also, as Olymprix pointed out, his less than perfect body represents that he's a less than perfect leader.