Mike,the stringer sounds good.I wouldn't see any way that a bow could get a twisted limb overnight.something does sound funny.I guess we didn't answer your original question.To check for a twist,on the unstrung bow,sight from one tip,across the front of the handle,to the other tip.The sight window should be close to center.You should be able to see one tip pointed away from center.If the bow is strung,sight down the other side and use the string as a centerline for sighting and see if one of the tips leans away from it. Now,occasionally a bow may get a slight twist from being in the heat,stored improperly etc. and often that fresh twist can be straightened by just hand twisting the limb back the opposite direction.Don't be afraid to twist it past center the other way.Often that is all it takes. I bought an old bow once and it was shipped to me in hot weather.It had a slight twist and I hand straightened it.It is still straight,several years later.I believe an old bow with a history of improper stringing won't be fixed that way. And I didn't mean to insinuate that you had used the step through method,mearly to say that odds were slim that your limb could be twisted.If it is a twist that just happened,I think you probably could hand straighten it. Also you can check by pulling the bow part way back and easing the string down.Does it want to track in the grooves or is it trying to go off center? If none of this works and you still think there is a twist,definitely call the builder.