Display Life (always on when charging with computer)

Hi!  Got my Sansa at Best Buy last weekend, and thoroughly enjoying it!

But, I noticed that the display is OLED, which is rated at 5000 hours of life at a few sources, with blue emitters wearing out the fastest.

I imagine that charging would mostly be done unattended on a computer overnight, meaning extended periods of display use (many hours). 

Anyone experience OLED displays dimming significantly after, say, a year of average use? 

I did try my Motorola’s USB charger but it doesn’t charge much even overnight.  SansaFix has had luck with his Motorola charger, though. 

Have a great weekend!