ah! yeah that sucks. It seems LND need the seed pharse PLUS the channel data. In order for the restore. https://github.com/fort-nix/nix-bitcoin/blob/4e5c5dfe9bdc05ba4b4d79dfa766a182ded0a3d3/examples/configuration.nix#L99 

 And unfortunately, if channel data is out of date, you risk taking a penalty transaction.