Yes, I'm pretty sure that is what it was. The only other snakes that large are the Eastern Diamondbacks, and there is NO mistaking them !!!
The only other time I've seen a Eastern Indido Snake was at a endangered wildlife presentation at a fair in Savannah, GA.
I'll never forget it. The guy came out with this gorgeous and big Eastern Indigo snake. He walked around in front of the people while talking in his microphone.
I watched the snake slither through his hands and then start nudging his wrist. I thought "uhoh" and sure enough, the snake casually latched on the guys wrist !!!
He had this khaki long sleeve shirt on and I don't think anybody else noticed it. He was such a pro. All he did was slightly raise his voice and tense up a bit. Then he just kept walking and talking while the snake held on to his wrist. LOL. He kept the sleeve low to try and hide the fact.
He finished up pretty quick, though, LOL.
Where I board my horse now I've seen all kinds of snakes. Mostly Rat snakes (they call them Oak snakes). I have seen quite a few Eastern Diamondback rattlers too, a few Copperheads and a really big Cotton mouth. The most unique one was a little rough green snake. Was as emerald green as a Green Tree Python. I saved that one from a barn cat.
Nights out there (spent a few with a sick horse) really do get spooky. The facility is carved right into the edge of deep woods, built on a old weapons dump. Coyotes run through there, wild pigs and just all kinds of animals. It is quite cool, when it isn't in the middle of the night.