Best Guess: probably means the level has been changed since it was last solved.
Expected behavior: This icon isn't something I expect to see, so I would expect some sort of obvious way to see more information about it, either by hovering over it (e.g. tooltips), by clicking on it, or by selecting the associated level. Icons are good shorthand but ultimately users aren't psychic, so if cause and effect isn't obvious some textual explanation may be warranted.
Expected behavior: This icon isn't something I expect to see, so I would expect some sort of obvious way to see more information about it, either by hovering over it (e.g. tooltips), by clicking on it, or by selecting the associated level. Icons are good shorthand but ultimately users aren't psychic, so if cause and effect isn't obvious some textual explanation may be warranted.