Does this sound like I need a bulb replacement?

[Steelmaker]

I have a Sony KDS 60A2000 tv. I bought it in March of 07. Here lately when I turn the set on, I've started noticing a faint "yellowing" around the corners and the edges of the screen. It's pretty subtle and not really noticable when there's a vivid picture being displayed but when it shows a dark scene or if the screen is black, you CAN make it out.

Can anyone tell me, is this the result of my lamp going out? The picture itself doesn't seem to be any dimmer, nor am I noticing any color fading. It's just that yellowish haze around the edges and corners of the screen.