I actually had this I fixed it and it worked!! I ride English so this is what I did and you can also do the same for western, but take ur rein a give a tug on ur horses but and if he makes an even uglier face then put him in a really tight cirncle spin him 3 times and then do the other direction 3 times also and that should help but if this keeps happening keep doing this method!!
Are there other horse in his pasture with sh/him.?and if he/she starts to act up id bake him/she up.!
If s/he lives with other horses there could be a possibility that they got into a fight with another horse and are just trying to protect themself. But I would suggest working near other horses, and when your horse tries to lunge out or pulls an ugly face, have s/he work harder. Then when they behave and focus on you allow them to slow down and praise them.