Recieved Write error but was able to use the BD-R again?

After burning 2GB of data with Nero I received a write error and the burning stopped.
I decided to try the media again and successfully added 15gigs to the disc. In the third attempt I used continue multi-session and added a couple more gigs.

The BD-R’s are Optical Quantum 25GB single layer.

Usually after a write error the media would be a coaster, is bluray media different?

Just wanted to update the thread to say that it was a combination of Nero and bad media.