Has anyone heard of het axanthics being black/silver as hatchlings, but then quickly (within 3-5 months) gaining their color?

I have 3 that were sold as axanthics that had absolutely no color as hatchlings. They now look completely like normals.

The seller is returning my $ and I'm sending them back... I just want to know if it's a sign that they're het for axanthic, and not just normals. Or is this just a fluke? There were siblings in the same clutch that were normals from the beginning.

I don't have any pics of them as hatchlings, but they were absolutely black/silver/white -- no color whatsoever.

Just curious if someone has had Het axanthics come out looking just like an axanthic, but then getting color within a few months. Is it a regular thing to have happen?

thanks guys.