Purple Spots On iPhone 5 Camera

Well, my iPhone finally has a problem that'll make me take it in for repair. (I noticed the screen had a "border", but I haven't managed to take a good picture of it so I didn't post, and it wasn't that serious, so I didn't repair it then)

The (back) camera has a purple speck, which shows up in all photos and videos (a bit bigger in videos), during preview and in all apps.

It's not on the frontmost element.

At first I thought I chipped one of the lenses, but it's almost impossible to chip the centre of something without touching it. So maybe it's a piece of dust. But isn't the camera module sealed? I found out - if you search for iphone purple spot, or something like that, this is a very common problem, all with the iPhone 5. And the spots all look similar, so it's something coming from the iPhone itself? I also found it interesting that when some people went to exchange their iPhones, at the end of 2013, when the iPhone 5 had been out for more than a year, that the staff said that they'd "never seen it before". That's impossible and makes me think "never seen it before" is something they're told to say.