Slide Off Meaning

Example: Used other than as an idiom: see slide,‎ off.
  Make sure your cup doesn't slide off the tray.
(Can we verify(+) this sense?) To leave a place, or a meeting, without being noticed
1982, John Le Carré, The Quest for Karla, page 162:
  Soon as he could, he slid off to Jim's rooms to make sure he'd left nothing around that a journalist might pick on if a journalist were clever enough to make the connection, Ellis to Prideaux.
2009, David Nobbs, I Didn't Get Where I Am Today, ISBN 1409066967, page 444:
  Susan and I slid off to an Indian restaurant in Shepherd's Bush, and I slid off on to the floor.
2011, Lamont Z. Brown Phoenix King, ‎& Lamont Z. Brown, Between the Gates of Heaven and Hell, ISBN 1426952619, page 10:
  As Simone and the crowd praised Drew I slid off to the back hurt, ashamed, and pissed off.
2013, Steven Gould, Impulse, ISBN 1429987545:
  I slid off to follow her and I heard the scrape of a board on snow.
  I'm going to try to slide off from work early, if I can.