A secret door and a stuck barred gate changed appearance the first time they dropped out of line-of-site

Found in Infra Arcana 10/17/21 master Windows build c078746a.

On depth 3 of a run with a level 1 War Veteran character, I came across a secret door behind hanging vines in the corner of a large room, and a stuck barred gate in a room just down the hall, that both changed their appearance the first time they dropped out of my line-of-sight after I had found them: the secret door tile reverted to blank wall, and the stuck barred gate lost its stuck "X" mark, looking like a regular barred gate; with both, when I moved back into LOS with them, they switched back to the visual state in which I had first spotted them. When I moved out of sight and back in again on subsequent occasions, they did not change their visual state--it only happened the first time they dropped out of sight and back in again.

I haven't noticed this with other secret doors or stuck barred gates, so I'm not sure how reproducible it is; I have this incident on video:

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