Also, Daystarwoman (nice tag, by the way :D), the tori apparently become more prominent in one's twenties and thirties -- which may account for the fact that you seemingly just noticed them. They probably weren't there before, or just were not as noticeable.
Peace.
Sounds like what's called a "simian shelf" to me -- which could be just another name for the perhaps more palatable (no pun intended) "mandibular tori." It's a carryover from our earlier ancestors and relatives (the great apes), a bony outcropping the purpose of which is to reinforce the jaw and give it greater strength. I have a prominent simian ridge around my lower jaw from wisdom tooth to wisdom tooth, and my niece (the daughter of my non-identical twin sister) mentioned to me the other day that she had one, too. So, I assume genetics plays a part in who does or does not have one.
I also have a bony ridge that extends the length of my hard palate (a palatine torus), giving the roof of my mouth sort of an "m" shape.
I've been told neither is a problem -- unless I need dentures later on down the line, which case some extensive (and, I gather) painful oral surgery will be in order.
Yuck!
Palatine tori also can obstruct a physician's view of the larynx, which can be a problem, as well.
"Race" also may be a factor in who has such bony structures and who do not. I understand that such structures are more common among Caucasians than blacks -- even though a study of Ghanaians revealed that fully 28.6 percent of the population studied displayed both types of tori. (Incidentally, if you have one, you're also likely to have the other.)
I happen to be African-American -- and, again, I have both (though, like most AA's I have white and Native American heritage as well, and fairly recently -- within the last three generations -- in the family lineage). I don't know what the incidence among Caucasians is.
So, not to worry. While the literature often seems to treat tori as some sort of pathology or "abnormality," they apparently are merely fairly frequent variances in perfectly normal human phenotypes (physical types).
It is prolly just a bony overgrowth that happens to about 10% of the adult population; it is called an EXOSTOSIS....simply thickening of bone an in the mouth due to unknown reasons.
Nothing to worry about however. You can see your dentist if you'd like.
Good luck
It sounds like a mandibular tori which is a normal outgrowth of the bone. See an oral surgeon for a definitive diagnosis.