What is he doing with his tounge?

I had my horse in a french link snaffle or a loose ring or a dee ring. And when I am doing his bending exercizes. Slide your hand down one rein and bring his his head around until her gives. He chews on the bit alot more doing this/these bending excerizes. When he was chewing and choping away while being soft and I bent down and lifted up he is lips and he has his tounge twisted under the bit and he's slobbering and just blah! If you need more of a idea of what it looks like take your tounge twist it with your teeth and you have a pretty good example of what it looked like. I have no clue why or how he's doing this! Has anyone else had this happen? What did you do? Any other guesses?
*At lessons he is in a myler bit and he seems to chews somewhat less.
*He had his teeth done in November.
*sorry for the threads and questions lately I am a nervous wreck before shows.

Why the different bits? Can't you put him in a myler all the time?? Once you find a bit that your horse is comfortable in, stick with it. Don't chop and change all over the place.

Thats only 3 bits I have tried. All being snaffles I wasn't expecting much out of them. The myler bit is my trainers I can't use it all week. And they Myler bits are hard to come by for a decent price around here. I was just wondering why he does this with his tounge in the first place.

Tasia, I ask about the bits, because I wonder if the tongue twisting is coming from discomfort in the bit, particularly if you say he doesn't do it in the Myler. It is possible that he is being pinched by a part of the bit when you take up contact on one side of his mouth. It is also possible that the shape of his mouth does not accept the type of bit you are using, it could be hitting him in the roof of his mouth, putting undue pressure on his tongue, or pinching his tongue.

There is nothing wrong with snaffles - most horses will go very happily in a mild snaffle, whether single joint or linked. FEI dressage horses *should* go happily in a snaffle if trained correctly. It is just that some horses mouth conformation and personal likes/dislikes lend themselves to the use of other bits than the simple snaffle. I know my little wb gelding is terribly fussy in the mouth, he chews, draws his tongue back, shakes his head etc. and has done so for many years before I started working with him.
Unfortunately sometimes you need to bite the bullet and just pay the money for a good bit. If the horse goes well in a Myler, and you can't get him happy and quiet in the mouth, in a snaffle, then I would be thinking of whether I want my horse to be relaxed, submissive and acceptant of the contact when I ride, in return for an outlay of money on a good bit. Or, also slightly resistant, backing off and not terribly happy, in a cheaper bit.
I know that I'd rather pay the money. I'm currently between jobs, have 3 horses, a car, a dog and a general living expenses to pay for, and I've still gone out and spent a lot of money on a bit that my horse seems to go much happier in.

Thanks for advice! I really hope I didn't sound snarky! I think I am going to bite the bullet and get the bit it seems worth the money by the reviews it gets.