Verbatim DL question



I have been burning Verbatim DL disc for about 10 months now on a NEC 6750A. Recently i’ve been getting discs that burn at 4x on the first layer and drop to 2.4x on the second layer. The discs are playable but I’m a little concerned by this. Does anyone know what causes this?



Probably the need for a firmware update. Then again NECs burners haven’t been too hot as of late.