I think you could experience something like this with any electronics. My LN46A850 was shipped to me (from Amazon) and I had no problems. It's been working fine for a few months.
If I'd got a replacement and the same thing happens - then I'd be upset.
I bought my first HD flat panel TV 9 days ago. The unit is a samsung LN52A850. Picture and sound were astounding ... I probably turned it on about 10 times overall and yesterday to my horror the screen is black and doesn't display a picture! I spend almost 3000$ on a TV that has trouble almost out of the box. I've read several other posts in this forum describing the exact same issue. I'm considering returning the TV to Best Buy and swapping it out for the Sony model that is comparable. The last thing I want is an expensive TV thats gonna be in and out of the shop or live a day beyond it's warranty.