Why is there a purple pixel ?

[Windows Central Question]

When I turn on my Microsoft Lumia 550 up in the left side of the screen , there is a purple pixel . After 1 second it disappears . The screen is clear after that .

 

[Dominic Stratten]

I noticed this on my phone today - you're not alone (Lumia 550)

 

[Thomas Wadsworth]

I wouldn't worry about it. I get it on 950