Last month, SWIM's results showed a slightly elevated hemoglobin level. SWIM asked the Dr. what could be the cause and she said it is usually from smoking. SWIM does not smoke tobacco or THC but has smoked the spice a few times leading up to the test.

It sounds like you've been vaporizing DMT, not smoking it. I doubt it does.

Smoking a few times will not raise hb.
Most common causes that I've observed are;

Long term regular smoking
Dehydration prior to blood test
Anabolic steroids

Then there are more rare and serious causes.

If your doctor was not concerned about the level of elevation, then I wouldn't give it a second thought.

Good news is those results were a month ago. New results show normal.