Kathy, there are always mold spores in the air. The stuff grows anywhere that there is sufficient humidity and the material has ever been open to the air. It grows pretty well in that plastic container behind the baking soda in your refrigerator, doesn't it? It didn't grow in the tomato sauce that was in the bottle but as soon as you exposed it to air, the mold spores take it from there. You don't even have to disturb the mold for the spores to be released.
The Tilex will work fine, particularly if you are more comfortable using it than bleach. As long as there is sufficient humidity though, the mold will come back. Painting the wall with a paint made for this may help some.