Am I the only one who noticed X-Men movie series screwed up a small detail in their last movie?

In X-Men 3: The Last Stand, Charles and Erik WALK over to Jean's house when she was a child. Charles was old and had no hair and was walking, so I assumed at that point that he was paralyzed after a later event. In their last movie X-Men: First Class it turns out Erik caused his paralysis when he was no older than 25. D:?