I know quite a few people ordered a size up. I did as well. I normally wear a small but ordered a medium. For me, I should have stuck to my guns and ordered the small because I have a small waist. The medium fit but then a medium in most things normally fit me just not as smooth and perfect as I would prefer.
I'm not complaining much but they stretch a lot so I am not sure about the need to order up, at least in my case.