It could be a number of things.
1. If the spot is v. small, i.e. a single pixel, it sounds like (on a white image) the green pixel of that group of three (RG & B) is dead.
2. If it's larger, like a patch, try moving the focus in and out. If the edges of the spot go in and out of focus, it's probably a dust patch which can be removed with a can of air spray (note, not hairspray )
3. If it doesn't go in and out of focus then it sounds like a burnt colour filter. In my experience it's the blue one that usually goes, creating a yellow patch, but in this case it seems it would be the green one creating a magenta patch.
If it's new and under warranty they should replace it if it's a burnt filter, and at least clean it if it's a dust spot, but if it's one dead pixel they may try to tell you that it's an acceptable error, although you argue that by being dead centre it warrants a replacement. Hope that helps
I'm glad it seems to be the lesser of the evils. If it's a new PJ you should find that they'll sort it out for you free of charge, although you may be without the unit for a week or so.
Alternatively, how squeamish are you about taking a screwdriver to it? I'm not personally familiar with the unit but it may be possible to get the access to the interior you need by removing the lamp cover and lamp (don't touch the lamp, even when cold. Any smear will degrade the quartz).
Give the exposed components in the light path a gentle blast from the aircan and try not to physically touch anything to avoid scratches, marks and possible mis-alignment, and you should be OK so long as you ensure you've not got a ciggie on the go when you do it and the wife's not dusting the sideboard next to the table you're working on.
If it's still there you could undo the case screws and remove the cover to get at the dust blob. However, there's a bigger risk of nausing it up and even greater need for a smoke/dust free work area, so it depends on how brave you are as it would be all at your own risk. Post back to tell us how it goes.