Fryovanni:
Most of my top braces are glued w/ a 30' radius form, and the soundboard was glued to the sides w/ a 15' radius form. We did this to help maximize volume and add tension. I made my braces pretty skimpy (thin), but when I glued them all up I made sure that they were all pretty tight. My back braces were glued w/ a 50' radius form, which the sides were sanded to the 50' radius form also (no tension built in on the back).
But like I said the dips arent very deep. I'm definately sure that the guitars sides were sanded to approx. .085" probly sanded .005" in the build process.. I wouldn't be suprized though if this particular section of the sides could be pushing .075". So I imagine like you said it could be a combination of things.
-sides being too thin
-humidity has caused them to expand (swell)
-the top and back are pulling the sides out of alignment
goodwood:
This is kinda the case. I remember when bending there were slight dips there before, but they were all sanded out. This isn't the first time I've run into this problem (like I said before). I fixed the problem on that first guitar, and just scanned it over the other day and noticed it has created little dips like these.
Personally I think what my biggest problem is, is the thickness of my sides throughout my build. B/c I remember when sanding the sides flat (after binding) there were dips like these. Also could be the unstableness of the wood before I started. I'm probly going to call some of my instructors and see what they have to say.