The boldface sentence above — taken from an open letter posted on Apple’s (AAPL) website by hardware chief Bob Mansfield — is something you don’t often hear from Apple. In fact, I don’t remember ever hearing it before.

The backstory, for those who haven’t been following this environmental minidrama, begins late last month when someone at Apple informed the Green Electronics Council that it was pulling its entire product line — including 39 green-certified desktops, notebooks and monitors — from the organization’s Electronic Product Environmental Assessment Tool program, and that the company would no longer be submitting new products for EPEAT environmental ratings.

No big deal, right? When it comes to electronics manufacturers, Apple is still about as green as them come.

The problem is that a lot of schools, businesses and government agencies insist that their IT departments purchase only EPEAT-certified computers — a point that was driven home earlier this week when the city of San Francisco announced that had stopped buying Macs.

The move seemed self-inflicted. All 39 products still comply with EPEAT’s standards. The outlier was the new MacBook Pro, whose batteries are glued to the frame and not removable with ordinary tools, as required by EPEAT. Moreover, Apple sits on some of the working groups that are trying to bring the standards up to date. (See here.)

Without explaining how this happened or who screwed up, the company has now reversed itself and put those 39 products back on the EPEAT registry.

It may be telling that the letter that admitted it was all a “mistake” was signed by the only Apple senior vice president whose retirement has already been announced.

UPDATE: Here’s an interesting development. Not only have Apple’s previously approved products reappeared on the EPEAT gold-star registry, but so has the MacBook Pro with Retina display, glued-in batteries and all. Go figure.