if you have entered ´now()´, the grid will show now(). If you next UPDATE that row, now() will be interpreted as a function – not as a literal. You can 'work around' this by working from the RESULT pane with a SELECT statement that does not include the column affected.
.. is not a problem for the last around 9 months actually as we since then only update columns that were updated by user. But I missed that the FAQ needed a small update here!