The way you described it developing fits with what would happen with transfer-related oxidation. I took that into account as part of the clues present.
Oxidation can give honey, caramel, and fruity notes, as well as dulling some of the other flavors. When you mix those all together, your brain might interpret that as candy sweetness. Beer has a lot of compounds in it, and those oxidize into many differently-tasting components. Hard to say if it's what you have, but you can probably tell more over time as these flavors will just grow. The bitterness can grow more coarse/harsh and thus seem more bitter. Other flavors dull, which changes the balance. Anyhow, that's how I perceive it. YMMV.