I had this issue with the front Rigida rim on my '82 Motobecane. In my case, it was actually opposite of the valve hole, where the rim was pinned together. The bulge was VERY slight visually (you really couldn't hardly see it), but quite noticeable when riding. It was so slight, I thought I might be able to just sand it out, but that wasn't working. So I took a set of large pliers and just gently squeezed on the rim to coax it back straight. To be honest, I'm quite surprised at how well it turned out. Braking is smoother than I thought it would ever be.

To be honest, I think I'm going to eventually build a set of 700c wheels for the bike to replace the factory 27 inchers, but they're working great for now.