(shared) has appeared in spreadsheet titlebar

Am sole system user and have noticed an odd spreadsheet showing the word (shared) in the middle of the title bar description. Persists over reboots. No other spreadsheets show this. Is this of concern and if so, how could it be removed ?

Build ID:
Linux Fedora 25

Check the share status of the document in Tools | Share Document

Thanks, unticking share status box removed it.