I think it depends how much there is? A bit of set is perfectly normal for a heavy bow, especially one that's been tillered slowly and carefully. The top guys can start, finish and tiller a warbow in about a day or two, which means much less time sat on the tree and much less string follow as a result but us mere mortals tend to have a bit of set at the end.
If you're talking anything up to about 2" I wouldn't bother going to the hassle of bringing the tips back (although of course, add a bit hypothetically to account for the tillering and shooting that will add some set) but if it's already over 2" and hasn't been shot or even tillered yet it might be worth gently straightening. I wouldn't flip the tips because you're instantly out of "English Warbow" territory (in fact, I don't even think it would be allowed in Warbow shoots if the tips are slightly flipped) but you can definitely bring the whole stave back straight or even with a hint of reflex if you apply heat carefully and in the right places.
Do it before you glue the plug in, of course, if you're going to.