He's a new addition, so maybe.... That being said I'm rather brazen with new additions. When I feed I take water dish and hide out. As soon as they coil I put the dish and hide back. I've even had to move the snake from one end to the other while they are coiled. Feeding response on these guys is instinctual. For the most part even feeding ft the coil and they stay like that for a min or two while the prey is "dying". If he dropped it, my guess would be it was a little to cold in the middle and freaked him out. The top could have scared him but next time just make sure it's warm in the middle, and then leave the top off until he's done, or quietly put it on.