Like Sally said. I would not be at all concerned about the subtle changes in color you are observing. Aloe vera (if that is what your plant is) can go through much more dramatic changes in color as part of its annual cycle, and none of them would be much cause for concern in my garden. The plants outside here go from green to gray to brown as the light changes and the rain comes and goes. Stay observant, but I'd put the changes you've observed so far as minimal within the overall range I would tolerate.
