DS2 has told one lie after another since coming home from school today. He's 4.9, and ate half of a chocolate bar DH had bought for me, claiming quite convincingly he hadn't had any before, and it was meant for him (he had already shared one with DH - I suspected this but wasn't 100% sure), he claimed DH had already given him his medication this evening (he hadn't), and he took a nice pen that I left on the countertop, and put it in his own treasure box, and then denied it.
This is new. I am :o and 
DS2 has struggled with social skills a lot, and this is completely new behaviour. Something must have clicked in his brain. Obviously if you have an NT child it's a pain, and he needs to learn not to lie etc etc but for DS2 it's a positive step as he's showing his theory of mind is developing. :o