This is normal behaviour as the holds targeter only checks for older holds once every 24 hours at roughly the hold request time. It would target the checked-in item the next day, but you can force it to re-check immediately by using the check in modifier Re-target Local Holds when checking in an in-process item, or by re-targeting the hold on top of the holds queue in the catalogue by selecting Actions for this Record > View Holds , or by selecting the hold in the patron’s record and selecting Actions for this Hold > Find Another Target.

For more detailed information on managing holds see http://docs.libraries.coop/sitka/_managing_holds.html#_retargetting_holds