Strange Bug: Sarah's Astral Outfit is gone

[Ciristhan]

Recently, I encountered the strangest kind of bug: When I got to Mt. Zulle I changed Sarah's astral outfit for a thermo suit to prevent the effects from the cold. And when - a long time later - I wanted to put it back on, the astral outfit was gone; I unequipped everyone but it still didn't show up.
Is there anything I can do? I have done so many quests since then and I really don't want to replay all of them.
Help would be much appreciated. Thanks!
Edit: Sorry, it seems that's what's supposed to happen - just checked some other posts; sorry....