Item disappears after being named on anvil. Have to leave and rejoin to get it back

I was naming my leggings using an anvil, after naming it, I left the anvil (pressed esc) and the leggings didnt appear. I search all around the anvil, dug above and below and could not find them. I did a search and couldn't find this bug. 

My friend suggested leaving and rejoining, which I did and the legging reappeared in my inventory. He says this has happened to him before.

I'm pretty sure this is a bug.