You are right! =) The object wasn't there before. And i know what happened... First i tried this side of the bunker (the easy one), but to open the safe i used a explosive (i don't have the lockpick skill yet) and then i did the dredge way...but with the door blocked i had to swim through the dredge again to get out.
i choose other skills more important to me..but i will get the lockpick to avoid this in the future then...lol
thanks for the feedback =)