To be honest from what i read there is nothing wrong with offering food during shed periods,most keepers do not do it because the ball python will more than likely not take the food while in shed,it is a rather vulnerable period for them so they cut off from feeding. Do not worry about underfeeding him right now,this is only one missed meal,that is nothing compared to ball pythons who went off feed for 7months and came back strong, i am not saying he will not be hungry but they can go long periods with out food and i am sure a few more days to a week will be nothing of a wait,so just wait until he is done shedding and then feed. Right now just let him do him and shed make sure your humidity is up and temps are good.