Yep, that's the sign of how well the unit is receiving the digital signal stream. P25 audio has FEC (forward error correction), and all the 1's & 0's not making it to the other end in the right order increases the error rate. The lower the number, the better.
You do have some control over the P25 adjust level... If you press and hold the "hold" button and turn on the scanner the screen will flash colors and allow you to get into the P25 settings. Then press menu and go to settings and then go to P25 adjust level. You will notice it is set to 50 for the default auto adjust setting. If you change it to 200 (press 200 enter) now the default level will always be 8 and if you change it to 100 the default adjust level will be set to 11. You can check this when scanning by pressing Func then press down on the volume knob, Func then volume again to watch the error rate. The setting of 200 works well for me but because most of the digital systems I listen level off around 8 using the auto setting anyway. If you find that the default setting works best just set it back to 50 by pressing 050 enter. You want to try to keep the error rate as close to "0" as possible. You may just need to move the radio around the room to get a better signal also.