Well, isn't it sort of expected?
It's a common misconception that LLMs residual exists for predicting just the next token. While training, we sum/average the losses across whole sequence which puts the pressure to predict future tokens on residual stream of _all_ past tokens. For example, if a particular shape of residual helps reduce loss across several future tokens, it will take that shape (even if it takes a slight hit on immediate next token).
What this means practically is that an LLM's residual contains information about all possible future continuations, or all possible questions that may be asked from a given context. So if you write "France is a beautiful country" in the context, I'm pretty sure it's residual would contain info about Euro, Paris and so on.. because all these completions are possible.
So, it is no wonder that you can find LLMs hidden state contains latent information/concepts that are never expressed, and yet related to a given context.