Update !
I spoke to an 02 employee today in my local retail outlet about the warmer yellow screen on the iphone 4.
'Oh we've not heard about that before', they said.
I showed them the comparison between their display model, and mine.
'Oh yes their is a difference', they said !
The employee even pulled out their own phone, and hers was with yellow tint too.
Asked how long i'd had my phone, which I replied was just under a month.
'Oh, we've have to send it off for repair'.
To be honest I prefer the warmer yellow as ive found after playing with the shop displays, I dont need to raise the brightness of my screen as much as the baby blue one, thus possily saving on a bit of juice.
I just wanted to test the reaction of the store staff and what they would offer as a resolution.
I ended the conversation by saying......
Apparantly an apple genuis bar will swap it straight away, I said, and the reply was 'oh, yes they will and remember to take the box'
Conclusion :
I kinda got the feelin they were guarding the stores stock with a three headed rottweiler guardian !! lol.