That's interesting, I guess whatever they're wearing there can be a danger of that, but with blankets you can easily remove one if too hot, whereas they're wrapped up in the swaddle of course. But unless you have your heating up especially high, I wouldn't have thought it a problem... Also if it's a commercial swaddle I'd have thought it would have ratings for suitable clothes to wear underneath at different room temperatures? If you dress your LO lightly and you feel they might be too cold, you could always pop a blanket over the top, just take care it's well secured.