TX-28DTX10 new possible prob?

hi guys, i have heard about this common fault with these tv's turning off randomly and its the av setup at fault with the Q link etc but mine does somethin wierd and i wondered if it was a bad sign!

basically when you turn my tv off i get a blue off shaped rainbow effect on the screen just off centre to the right hand side that glows and slowly but surely fades away to black like the rest of the screen, is this ok or an indication sommits wrong?

i mean i dont really mind it doing this it dosent affect me i just got it new you see as an ex demo model and dont want to be accepting it if its a bad thing

cheers lads

martin