I think it would be fine to get the moss damp again and just check that he is okay. If you notice that he looks back to normal, don't worry! They clear up right before they shed.
As for ingesting aspen, it really isn't a huge deal. They digest bone just fine so a wood chip here and there shouldn't bring need for concern. You can probably start feeding him something much bigger. Hatchling ball pythons are started on hopper mice (bigger than fuzzies) and quickly move to small adult mice. If you are uncertain if you are feeding your snake enough, pick up a kitchen scale that weighs in grams and weigh your snake and the food. Your snakey should be eating 10-15% of its body weight every 5-7 days.