Are you asking us if it's acceptable to you? Only you can decide if it's worth sending back, if it annoys you or bugs you, send it back, it's very likely you'll get a replacement as most retailers seem to be accomodating when it comes to dead pixels, even if not, kick up a fuss and you'll normally get your way.
Bear in mind it could be a hassle, so weigh up how obvious or annoying it is compared to the annoyance of having no tv and having to box it up and set up a new one.
Information of pixel defect
Plasma screens display information using pixels. Pioneer plasma display panels contain a very large number of pixels. (Depending on the panel size; over 2.3 million cells in case of a 43 inch display, over 2.9 million pixels in case of a 50 inch display, over 3.1 million cells in case of a 61 inch display). All Pioneer display panels are manufactured using a very high level of ultra-precision technology and undergo individual quality control.
In rare cases, some pixels can be permanently switched off, or on, resulting in either a black or coloured pixel permanently fixed on the screen.
This effect is common to all plasma displays because it is a consequence of the technology.
If the defective pixels are visible at a normal viewing distance of between 2.5 and 3.5 meters whilst viewing a normal broadcast (i.e. not a test card, still image or single colour display) please contact the supplying dealer.
If, however, they can only be seen close up or during single colour displays then this is considered normal for this technology.