3gs light sensor issue?

I'm using an old 3gs and I've noticed the light sensor isn't all that responsive. Usually in really bright daylight it does adjust a bit but under varying indoor conditions it doesn't change from a usually low backlight setting which I then have to adjust manually.

One time I put a flashlight up against the earpiece/sensor area, in a dark room and it took several seconds for the screen to brighten up. I then waited for the screen to go back down once I put the light away but nothing happened.

Is this normal for the 3gs? The searches I've done show results for broken sensor ribbons or water damage but this is phone kept in good condition and never tampered with by it's original owner.

I tried clearing memory, it's the same thing.


@Chambone - That would seem to be the case. I've only noticed it go down after manually pressing the top button to shut off, and then press it again to turn the screen back on. I've also observed the lockscreen is always brighter regardless of how dim the menu screens are.