Hi M.,
Are there any other sensitivities you might have noticed? Immediately it sounded to me like it could be sensory related. There are many Web sites and books out there, one book is The Out of Sync Child. A Web site you can look at is http://www.sensory-processing-disorder.com/index.html. Some of it may or may not ring true for you.
Everybody has sensory issues to some point. For example, certain sounds are unbearable -- a typical one is nails on the chalkboard or high-pitched loud squeals. When somebody says they like a food but can't tolerate the texture, that is a sensory sensitivity.
I've done some research because my 3-year-old overstuffs her mouth to the point that she gags, for example, or always has a finger in her mouth. She loves fruits but only strained, even still at age 3, because the skins and seeds make her gag.
I haven't had any testing done, though I know funding and help are available if a diagnosis is achieved. I have just tried to research and use methods to help her, like brushing her teeth before meals to stimulate the mouth and give sensory input (you will read a lot about "input" in researching this). I haven't sought testing because I'm not sure I've seen proof that her issues are not just a part of her age. Many kids outgrow their sensitivities. But if it's interfering with daily life and happiness of the child, I might bring it up to the pediatrician.