Same thing I'm experiencing as well, I'm wondering if it's normal. I just got my Twist in this morning and have been using it all day. I find that when I'm dripping with an atomizer the top portion near the button tends to get pretty hot. I'm assuming it's because the atty is obviously heating up.
When I'm using my Stardust though, it does get warm up top eventually, but no where near as hot as it does with an atty (LR).
Needless to say, I won't be chain-dripping with this Twist as much lol.
I am loving the Twist though, I'm thinking of picking up a 2nd one. Just also wondering if the heat up top is normal/anything to worry about.