The "3X" Theorem
Whatever amounts to "sensible communication," triple it!
Play back the last 24 or 48 hours. Is there an instance where you have failed to Fully Inform a client, or other stakeholder, of a delay (wee or grand) or glitch (wee or grand)? If your answer is "nope, all is well"—you are a liar. (Sorry, it just slipped out of the keyboard.)
Make the call.
(And if you have, in fact, good for you, let someone know about a glitch ... call 'em again to update the status of the fix, or relay the sad but honest news that the fix is more complex than first imagined.)