If you cast a fishing rod, drop it and then pick it up again, the textur will be the one of the cast fishing rod (whitout the black line to the float ball) when you select the right slot.(even if it is uncast) When you left-click on the item in your inventory, you see the right texture but when you put it back into your hotbar it has the wrong texture again. You can´t do anything about it then reopening your world.
Edit: also if you cast a fishing rod and then scroll over to another fishing rod in your inventory, the same bug will appear(like in MC-173013)