iPhone 5 screen scratches from the inside?

A little odd. I wouldn't be concerned that you can't feel it. I've never used an iPhone without a screen protector anyway. That'll solve your problem for sure.

 

I'd go back again to Broome for the jewelry & beaches.

 

How can we explain a scratch we cannot see on a phone we do not have?

The phone got scratched somehow. I would do what you said you were going to do and that is toss a screen protector on it and move along.

 

people will find what they look for

 

Do you have a cat in there?

 

What the OP describes is not off at all. Every used iPhone I've ever set my hands on (dozens) has had some hairlines scratching. It's basically normal wear and tear. Dust, dirt, sand, etc enticing ably gets in our pockets and purses and causes these micro scratches. You can't feel it because your finger isn't sensitive enough to feel a minuscule scratch like this. If you have a vehicle that's a couple of years old, especially where they sand/salt the roads, you will see this in your windshield too. Rub your fingers against it. I guarantee you won't feel that either. Same difference.

 

I've never used an iPhone without a screen protector anyway.

 

It's not actually the glass that's scratched. It's the oleophobic coating, that's why you can't feel it with your fingernail.

 

Never understood why folks place so much time on finding things like this. If it doesn't affect the device during use. Then it's a non issue.

OP, don't know what to tell you about why its there but I wouldn't worry. Just enjoy your iPhone.