GvE time for completion - possible bug

Hi, I was watching the completion timers and noticed that the top guild’s timer went down by a whole minute after the entry period closed. When they finished, they were at 5:18 min, but I checked back 30 mins later (after the event was over) and their time decreased to 4:18 min. The only thing I could think of was that they entered the GvE event last minute and completed their run after the entry period closed. Not sure if this was a bug exploit or their time was initially displayed wrong, but something is definitely not adding up and should be looked into it to make sure GvG/GvE is fair. Happened on NA-EAST Regulus with Alteisen island, but could have happened with other GvE islands as well.