I’ve realized over the years that a message along the lines of – “got 15 minutes for a quick chat?” – that feels even a touch out-of-the-blue from a colleague means –
(a) They’re leaving the company (or in a rare case have a very good offer) (60%)
(b) They’re becoming a parent and going on mat/pat leave (30%)
(c) Other – e.g., they were annoyed by something did or need quick help with something personal (10%)