Would love some advice!

[Pil]

[I thought I posted this already but it never showed. Apologies if it's a double]

Howdy, I'm brand new to this site and to Plasma/HDTV/Blu-Ray etc. so I hope I don't sound completely foolish (I think I've done a "decent" amount of research).

I bought a nice shiny new 50" Samsung PN50A550 last week along with a PS3 for Blu-Ray.

Setup was easy and the picture quality is phenomenal! As I'm sure many people who just spent $2500 are (especially those like me who've never owned a plasma), I was pretty nervous about burn-in and image retention. Imagine my horror when after playing a little poker (about 20 minutes) on Xbox 360 I noticed very visible image retention on stationary parts of the screen! Since I'm well under the typically suggested 100 hour break-in period I've now toned down the contrast to 50, cell light to 0 and made some other black level adjustments.

What I'd like to know is:

1) Is this typical? Should I be worried? I know in general burn-in and image retention aren't a real issue anymore. But, should I be concerned that I may have a faulty TV since I'm experiencing this?

2) If this is normal does anyone have suggestion(s) on settings, usage, etc. that I should be using during the break-in period?

3) I bought my TV from Best Buy and did NOT get the 4 year warranty. I've got a few weeks to go back and add that should I feel the need. Should I? For some reason I always feel like those extended warranties are just an easy way for companies to make more cash. Maybe I'm wrong?

This site has been very informative so far, thanks for your responses!

-Pil

..