light blue spot on screen for iphone4

I bought iphone4 4 momth ago.
Two weeks ago, I found light blue spot on iphone.
Spot size are width 5mm height 15mm , located on middle left.
Lastweek, I visited apple as center located in technomart , seoul. korea.
Staff took a picture for iphone spot and sent email to apple center.
Because the cause of sopt is whether user's fault or not.
Yesterday I called from as center. He told me the spot was made my fault.
If my fault, only finger touch on screen.
I think it was absurd treation of apple policy.
please help me.
What can I do for this action of apple?

Message was edited by: BlueLee