It was annoying so I tried tapping the screen and it's gone now - is that normal for these TFT screens????
Yes. Unfortunate, but normal.
If you read the small print you'll find that the majority of manufactueres will not consider this "defective", and depending on the make/model it may not qualify for a return unless you have more than a certain number of stuck pixels. The only one I can think of that will doa return based on a single bad pixel is Phillips, and even then just in Europe. Most brands require at least 4 bad pixels, and the no-name budget brands won't even talk to you unless you have *dozens* of bad pixels... This is why it's a good idea to stick with the name brand screens, or get one from a store that has a no-hassle return policy. (You have much less choice when you get your screen from a department store, but it's a *whole* lot easier to deal with in case there's any problems)
Any minor defects can be really anoying -- consider yourself lucky that you were able to flick it and make it go away. My current 19" LCD had a green pixel pop up that went away by flicking it. My previous 17" had one that was permanently stuck on red, right smack in the center of the screen, no matter what I did. Just had to put up with it. :-?
When using the windows GUI it was near invisible, but it can be extremely distracting when playing an dark game or when watching a DVD.
Depending on what the problem is, there is another possible fix -- having your screen cycle through red-green-blue very fast for an extended time can sometimes unlodge stuck pixels as well. If neither flicking it nor the color cycling works, then there isn't much else you can try.