For those who are still curious about the white iPhone 4 thickness issue, here’s a quick update from a leading case developer—one that has done an outstanding job in the past of tracking even minute mid-production differences between iPod and iPhone models.

Are the latest white and black iPhones all thicker than ones that were originally shipped, or are just the white ones thicker?

“Just white,” says the developer. “It’s thicker on the plastic portion that sits between the glass and the metal antenna. Most images aren’t measuring this.”

Is it perhaps only an issue of manufacturing tolerances? No, says the developer.

“There are always variances in devices and Apple is typically one of the most consistent, in large part because of materials, simple design and precise processes.”

This difference, we’re told, is easy enough to accommodate—at least, in cases being manufactured now. But something else is a potential challenge.

“Proximity sensor is the real issue here,” the company noted. Cases or screen protectors that aren’t cut properly may have issues triggering the sensor accidentally.

As noted in our white iPhone 4 supplementary review, we had no problem getting prior-generation rubber cases to fit properly on the white iPhone 4. The thickness difference was apparent but very small, and certainly not a big deal for most users or cases. Only the most tightly contoured hard plastic shells would have an issue with the new model. Still, between this little change and the ones in the side switch and volume buttons of the Verizon iPhone 4, iPhone case manufacturers have had a pretty tough time making post-release adjustments this year. Some will obviously accommodate the differences more impressively (and openly) than others.