Yes the gray scheme was a test and wasn't adopted. I think there may have been more than 1 in Gray and more than 1 scheme according to something I've read on the net.
Edited to add:
Article about the 'Gray dragon' here:
https://theaviationist.com/2013/02/2...-dragon-story/
Comments further down make reference to a 'Gray Ghost' aircraft included in trials in the mid 1990s from someone apparently there.
There was also a 'desert' scheme on one F-117A.