I genuinely thought thats what was happening when they were escaping the subspace rift and she said areas of her hull were burning away, assumed the old hull was what was underneath like a snake shedding its skin.
Were you remembering when the Cerritos shed all her "outer hull" bits? Because now it's canon.....we saw it happen.
Though the idea of multiple layers, especially now with the programmable matter malarky, is actually not a bad idea.