[Amps] AL-572 Negative grid current?

[Scott Manthe]

OK, I have taken all the tubes out of the AL-572 and put only 1 in at a 
time and turned the amp on each time, with the same results: a slight 
negative pulling of the grid current meter and then a slow rise until 
it's almost at zero. I also plugged in a never used tube that I received 
from Ameritron Wednesday and it causes the amp to do the same thing.

I'd guess all these tubes cannot be bad, so what gives?

Also, a new twist- if I shut the amp down and then turn it back on 
quickly, I don't get the negative meter pull - it just goes back to 
reading slightly below zero. Slightly mean about .5 to 1 mm.

73,
Scott, N9AA