Chewing on the bit.

Question
I have a twelve year old Arabian mare and she has just started to chew on the bit. I have ridden her on trails and in the pasture. She never did it until about two weeks ago. I use a snaffle, with the rollers, on her. She only chomps on the bit during a trot any other gait she doesn't. When I loosen the reins she stops, but they are then too long for showing standards. Is there anything I can do to make her stop?

Answer
Hi Hannah,
Thank you for writing in with your question.
I would normally suggest going to a roller bit...but you are already using one. The next step I would suggest is having the mare's teeth checked. She might have some problem with her molars. When there is no pressure on the reins, the bit sits soft. When you take up the reins, the bit moves back to rest against the molars (which it shouldn't do) causing some possible discomfort. That would be my next option.
Good luck with this and I wish I could be of more help.