Jail ?

Minecraft Username: doctorwow
Punishment and Duration: jail

Hi, I was recently jailed and I'm not sure why ?
I did go to the nether shopping area the other day and got some honeycomb but I may have paid for it wrong. I gave one diamond for 6 stacks I think and I put the Dimond in the ender chest by the door.
If this is what I've done wrong I will return the items or pay the appropriate amount. Sorry to the shop owner, I did not mean to steal. 

if this is not the case, I except the punishment but will  just like to know for how long it'll be