Could be, but kids are not like us, they can be barfing one min. and up playing the next. I think it is a good sign that they are up and playing. The diarrhea is just the bodies way of getting rid of the rest of whatever made them sick in the first place. I wouldnt be like all up in their faces playing with them and such for the next few days, but I think as long as you werent there when they got sick, that you should be fine.