There could be hundreds of reasons for it.
Maybe he/she hadn't digested her/his food yet and that was bothering her/him
Temp changes / viv changes could have caused it.
Maybe you moved a bit to quickly which startled him/her or maybe your toe or something was mistaken for food lol
Remember if your going to be handling that you don't want your snake to think your scared of it don't be hesitant or pull your hand away when he/she moves.
Please don't take this the wrong way but considering you have a relatively expensive snake I would have thought you would have had you husbandry sorted before getting it. From example. A thermostat one ALL heat sources, thermometers to keep track of temps (I'm assuming you don't have any as you said you didn't know your che had gone and could have been a while) and read up on all the ways to keep humidity up in the tank.
Good Luck.