Your viv setup isn't really right for a corn.
1) Corns are primarily nocturnal. They are most active at twilight and evening. They do not need (nor want . . remember, they have no eyelids) artificial UV lamps. Some reptiles do, but not corns.
2) You want belly heat, not overhead heat for corns. It really doesn't matter what the temp is at the top of the cage or out in the air [within limits of course, don't bake or freeze them]. What matters is the temps where they are...on the surface of the substrate or just down below it for the burrowers.
Get yourself an Under Tank Heater to use for the viv and get rid of overhead heat or uv lamps. Get a thermostat to regulate the UTH, set the temp to mid-80's, and measure the temp at the hotest spot the snake can get to (basically on the glass right over the UTH). That temp should be in the 82-86 degree F range.
3) Get rid of the pine shavings. Aromatic woods contain oils that are toxic to snakes, including Pine. Although some folks do use pine shavings so pine is probably less toxic than other aromatic woods. Why take chances though? Get him off of the pine and put in the Aspen. Aspen is safe.
4) You want at least 2 hide-away areas for him. One on the warm area over the UTH and one on the cool area on the other side of the tank. [and put his water dish over one the cooler area or in between the two areas]. Small and young corns will appreciate more than 2 hide areas, but 2 at a minimum. Also make sure you've got some ground cover for him. Young corns like to feel hidden away from potential things that might want to eat them.
5) It's generally recommended that you not bother them for a week or so after you get them, so they have time to settle in. Too late for that now, but you might want to keep handling to a minimum for a week or so.
The tail rattle is both a warning -- "Hey I'm a scary snake...don't eat me!" and a sign of anxiety or excitement (one of my boys tail rattles whenever he notices food being presented to him).
Young corns are often quite nervous about a lot of things, they are after all near the bottom of the food chain right now. Most get calmer as they get bigger and come to realize that you don't intend to eat them (not all, but most).
Have a look around at some of the other care sheets and viv setups, and you should be good to go. Welcome to the corn addiction