Naw, it ain't no BS. That stainless is some weird stuff. It shrinks more as it cools than mild steel, so some of it's tensile strength is used up just holding things together. And stainless doesn't always grow and shrink the same amount as it is heated and cooled, which is part of the reason it pulls so much when welding. Even welding stainless with stainless is easy to mess up. The different alloys in the SS cool at different rates and have different critical temperatures, so the composition of the steel can actually change into something else. The hot-shot welders at work say to quench a 316 ss weld so all the alloys fall below their critical temperature at the same time. The old guys use a rag dipped in a bucket of clean water on their TIG welds to cool them. Us millwrights just toss the thing in the bucket while it's hot. Using a guench and a clean SS wire brush while it is still wet will clean it right up to shiny silver without the bronze color that it can turn to through the entire heat affected area, too. The discoloration is hard to get out if it isn't done right away.
What's really neat is to watch an experienced pipefitter change the radius of an already wleded 90º elbow by heating small diamond shaped spots and cooling it down with a hose. Seen a few pumps stress-relieved that way so they will stay in alignment.
Keep in mind, though, when considering any advice I might offer that when the mill starting reguiring every weld to be made by a certified welder, I didn't even bother turning in a coupon. I just took the fancy electronic welding hood they bought me home and let some other fool do the welding at work. Same pay. Who says millwrights are dumb?