It could be the type of tobacco you're smoking -- it would really help us to know what it is -- and, as Jud said, the fact that it's not broken in yet.
One other issue I've seen with cheap pipes -- and if it's branded, it would help to know the brand -- is that some are actually varnished with a shellac that gives them a beautiful -- and permanent! -- shine but which makes it impossible for the briar to breathe. The one varnished pipe I've tried would only smoke hot, and even sanding off the coating didn't help. (Probably because it was used on briar that hadn't been properly dried/aged.)
Varnished or not, if the briar wasn't properly dried and aged, that could also contribute to an overly hot smoke, which in turn could lead to bite. And the odds of that being the case are higher with a low-priced briar than with something that cost, say, in the $80-100 range.
Finally, and this is probably the least likely scenario, you may be encountering an adverse reaction to perique (if the blend contains perique). I experience this myself, but I've never encountered anyone else with the same problem: When I smoke a blend with perique in it -- no matter how small a portion -- I get a sensation like needles piercing my mouth. When I was a younger smoker, I called this "tongue bite." I've since discovered it's more like an allergic reaction. But I've discussed this with a number of tobbaconists (and even Greg Pease) and they've never heard of anyone else having this kind of reaction. But I'll throw it out there, just in case.
Bob