Negative, I did re-expose.
I was also playing around with re-developing negatives.
Not sure if there is a real advantage. I did some Pro 400H with the above method and Rodinal, 400H is already grainy, but this was grainier, but not in the usual sparse 400H way that I dislike.
In the 400H example, I used E-6 colour developer as mentioned above, it results in a neg with a green mask instead of orange doing that.