Curse appearing on item that I've had for days

[Green Monster]

While fighting the big mimic in the minotaur cave my MaA's tower shield got unequipped. I had gotten it (from auction I think) a few days ago and it had been +3 with +1 fire damage and some not terribly important extras. After mimic removed it, though, suddenly it's a cursed tower shield with no special properties.

[Kitunenotsume]

That is a possibility with cursed items, that the curse can appear some time after acquisition, if the conditions are met.

While unfortunately light on details, the Wiki page has a few more examples: https://wiki.bgtscc.net/index.php?title=Cursed_Items

[Green Monster]

That is a possibility with cursed items, that the curse can appear some time after acquisition, if the conditions are met.

While unfortunately light on details, the Wiki page has a few more examples: https://wiki.bgtscc.net/index.php?title=Cursed_Items

Thank you for the explanation! I wasn't aware of that a curse could wait until it's equipped. It's possible that that was the first time my MaA equipped the tower shield, she usually uses a heavy shield with +1d6 neg damage bonus on it.

[Lockonnow]

is there a way to spot this curse and remove it?

[Kitunenotsume]

is there a way to spot this curse and remove it?

According to the wiki page I linked above (emphasis added):

There are several ways to discover if an item is cursed,
The most obvious one is equipping it. People with a high Lore or Spellcraft skill may be able to spot the curse before that happens though, for example when they first acquire the item. The difficulty class for detecting a curse depends on the cursed Item's worth. Items with high value have curses that are harder to detect. An Identify or Legend Lore spell will also assist a careful adventurer.

Presumably, one could also just regularly cast Remove Curse on ones inventory after a loot run, if it is a spell one has available.