Yeah, just email AACOMAS to be certain. They're good about writing back pretty quickly.
@jonnythan has the right info above, but I want to say that if it's an undergraduate course, it will be calculated in your post-bacc GPA, not graduate. Their going to know that an undergraduate course was not part of any graduate degree program.
For the record, I took a ton of undergraduate courses after my Bachelor's degree and while enrolled in a graduate degree program. I calculate them under post-bacc, not graduate on my own running GPA calculator.