Death Bug while leaving LAN-World

I started a LAN-World as host and let my other Account join to test out some things, basically I killed myself then and used the option to leave the server directly in the death screen, after that I logged back into (remember i was the host) and I was alive BUT I was able to fly through blocks (I died in Creative Mode)

EDIT: seems like this happened only once, not sure if it was Mojang's Fault.