Unless it really doesn't bother you than i suggest keeping it. But if it does bother you than i'm sure you're still within your 30 day return period and should exchange it at the store. If i had only one dead pixel and zero flashlighting i would be completely happy!
If you notice dead pixels, sometimes you can massage them back to
life just rub the screen by pressing a finger gently through a soft cloth
around the pixel. No guaranty but sometimes it works LCD's are
fairly fragile, so take it easy.
I just got my Samsung LN40A650. Its an amazing TV. I've been following this forum while I waited for my TV to arrive. So after reading all the good and bad stuff, I was pretty nervous. I checked for the flash lighting and clouding people have seen , but this set looks pretty even on a black screen, just slightly brighter on the right side, but I've dropped the backlight down to 4 and its like perfect. I'm assuming this will get better in time. I did notice (1) dead pixel, I think its dead. It shows up on white back ground or light colors. Using those Red, Green, Blue and Black back grounds it doesn't show up on the red, black and blue ones, only on the white and green ones. On white it looks a little red colored. Anyway Its in the upper right so its mostly blocked by my PS3 clock, but does show up when I browse the internet via the PS3, I guess I could try and avoid white web pages
Its kind of bothering me, I thinks its just cause I know its there and I paid so much money for the TV. Its probably the best spot for a dead pixel if I had to have one. Is it possible for these types of problem pixels to fix on their own, kind of like the the flash lighting and clouding issues?
I would like some one to tell me its ok, your better off keeping it then possibly getting one that's worse and has flash lighting.
Thank you for your support and opinions!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic