Phillips drive have a new feature called Walking-OPC (I am sure I am not telling anything new to the senior of this forum)
Here's a description of it's behaviour
[I]To ensure optimal writing quality over the entire disc at higher writing speeds, Philips has introduced the Walking OPC algorithm. WOPC directly measures and optimizes the actual writing quality during the writing process.
At certain intervals, the writing process will be briefly interrupted, the writing quality directly evaluated and the writing power adjusted accordingly, if required[/I]
This indeed look a lot like the behaviour of my Pio, Thanks to TerminalVeloCD for pointing this out, Too bad Pio doesn't write it in their feature list!