Just some thoughts after thinking about this image and the other frames that I captured last night.
What I realized this morning is that I did not capture enough frames with this set. When capturing the shadows, I need to make sure that there are enough frames to capture the detail there. I think that what happened when I merged to HDR is that there were gaps in the information (detail).
The other thing that I had changed in my work flow was that I switched to manual and therefore the man in the loop caused a bit of lag in image capture. When I started shooting this scene the light continued to fall off even though it was late in the evening. When I arrived, I was able to expose at f/11 for 30 seconds at ISO 100 and 10 minutes later I had to go to ISO 800 to be able to capture the same exposure. This and the fact that I was only grabbing 3 frames contributed to the problem.
So the issue may not have been the ISO per se, but the post processing that tried to make something out nothing (you can't create detail if it is not there).
There is kind of a dilemma when you are trying to post a "quality" photo a day (not that I have achieved any kind of quality yet) and you wait to the last minute to try and capture an image and that is compounded by being called home early for some reason or another. Not a big deal really, just a little frustrating. There has been at least 6 times to date that I would not have posted anything because the image was either of poor composition, quality or not an interesting subject. I really need to sit down this weekend and come up with an overall plan to keep the images interesting and organized by some sort of theme.