Is my psp screen ok?

Me and my friend both have a psp, ibought mine recently and have firmware 3.40 and he bought his last year year and has firmware2.80. I noticed that wile looking at the same picture on both psp-s mine has slightly colder colors they are both at the same level of illumination. It works great but is it broken or it is just different. I can not exchange it because i bought it in Barcelona and I live in Serbia.