I asked the same question. Answer I got was that Lazarus paid for his sins with his death. But since Jesus hadn't died yet if Lazarus sinned again then he would become imperfect again. So Lazarus must have sinned after being ressurected and before Jesus died.
Which just sounds like a stupid loophole Gods lawyers came up with after the fact.
But even so. What about the kid who fell out the window and died after Jesus death? He should have been ressurected perfect, and then any further sins would be covered by the ransom!