something to remember is that to a snake, particularly a young one, you are a predator. they don't understand you are nice and want to take care of them right off. that being said they mostly want you to go away.

it is good that by changing its setup you are getting "better" behavior from the animal, though. just remember the best way to approach them is with firm, direct movements (I don't mean squeezing them). If you open the lid and it comes right up to the top that doesn't mean its after you, it could be exploring and just want out, it could be hungry and looking for that mouse, or it could just be an outgoing snake.

If you put your open palm in front of the snake does it track your hand with it's head back an cocked, or does it just pull it's head back (both can look like an "s" shape, but mean totally different things). Even if it looks like it's after you, if you can firmly (not showing fear) reach somewhat behind it and pick it up mid body, it will probably get over itself.