My Reply:
The simple answer is clearly, yes. Telling a white lie is well known concept that illustrates this perfectly, which Jedis did too. In doing so, they were dipping their toes in darkness in their fight for the light. A slippery slope at times for sure, hence their dogma. A perfect real world example of a fallen Gray Jedi, is a person fighting against racism that moves on from trolling and ridicule to unprovoked violence in the streets. At that point, they have became the monster they were fighting, as the old saying goes. Or as another saying goes, they have been stared back at, by the abyss at which they gazed. So, our heroes were being Gray Jedis in their lying moments whether it was called that or not.
25 Things The Jedi Aren’t Allowed To Do In Star Wars
https://screenrant.com/star-wars-jedi-cant-do/#tell-lies 
It gets more nuanced to be sure, but that is all that is needed to prove the point. That said, here's a few deeper things to ponder. Was Mace Windu being Gray when he wanted to bypass the corrupted system to get rid of Sidious? Would that have been a better path? When Yoda essentially warned Luke of even dipping ones toes in evil less they become consumed, was that an absolute (Sith) truth or him trying to protect Luke? Is the Jedi dogma much akin to religious dogma of monks and priests? Does that class of people ever do bad things? Has a saint ever done bad things? Has a person that was Why does the Yin and Yang symbol have dark in the light and light in the dark?
Have a good day my Grays!
Here's some excerpts from an article purporting to debunk my point while actually proving it...
Star Wars: Why George Lucas Says There's No Such Thing as Gray Jedi
https://www.cbr.com/george-lucas-gray-jedi-exsistence-expalined-star-wars-disney/ 
