I think that a game engine converts the model to triangles, so when your exprorting them out that what your getting.

As for using Quads, the layout of the mesh is cleaner and I think that they are able to deform better when you setting up the character. Also if you go to sub d's triangles give some strange geometry and wont render in mantal ray (up to maya 7) (the subd not the poly)

If your making characters for games then the odd triangle wont matter, as its converted.

If I'm barking up the wring tree then please tell me as this is my understanding at hte moment..