Um, I don't think it's intrinsic to MT to drop your hands. At most I've seen dropping the same side hand in a swinging motion similar to a roundkick, while keeping the other up.
Regardless, it sounds like your are either doing the kick too slow or are doing something to give away that the kick is coming, if it is getting caught all the time. In general, it is most effective as a stopper, when the opponent is coming in. If you are using it to set up a combination, rather than as a distance controller, you need to make the opponent focus on your hands first.
If it is happening because you throw it a lot, start to mix in feints and tricks. For the lead teep, I will change height of the kick, switch to a superman, switch to a brazilian style head kick, fake into a step in knee ect to keep the opponent guessing.