I think you're just seeing a fairly normal lag in processing foreign transactions. Because you booked through the Korean site, it sounds like your transaction may be considered a Korean-initiated transaction and is beng batched with others, routed through transit banks, and converted to dollars, etc. I've had tix on other foreign sites like Ethiopian and Egypt Air bill through after completed flights and returned home. It makes filing timely expense reports frustrating and you may incur a currency exchange fee.