Hi & welcome to LQ. Sorry you didn't get a response to this.
It might be because the 'live' .iso user password is just <enter> (nothing)
(and then sudo wouldn't ask for a password).
Or maybe more specifics on what 'state/situation' it was in when it asked.
(if so, can you describe further)
Or maybe you found a solution.
Anyway, best wishes! Hope to hear more from you, about your Linux journey!
