A century of change in compound words

I hadn’t noticed until I checked the manuscript with Grammarly that many words we write as compounds are separated in these old letters.  Perhaps it was one of Uncle Charley’s quirks, but I have found similar instances in other writers. 

Language changes over time. We now compound word pairs like “state room,” “light house,” “to day,” “up stairs,” “worth while,” “every thing,” “dug out” (canoe), “bow sprit,” “center board” and many others.

The Grammarly program, which goes beyond ordinary spellcheck (that word is both new and compound) flags those now-compounded combinations for me. I make the corrections if it’s my writing, but leave the words as is if I’m quoting an antique letter.

Been there? Done that? Read the book? What do you think?