Did they have it at the lfs? Maybe they are not used to it? It doesn't particularly matter as long as they are still eating it. If other fish are eating it - keep feeding it and they will probably start to eat it.
In other words, don't worry
If you want to get them used to proper food, try daphnia. I use pre packed sachets from Tetra. My neon's love both bloodworm and daphnia now.