I do see it all over like this from time to time Brian.
Do this:
Spray it with household ammonia. The red should disappear, but will come back when the pH shifts back after the ammonia evaporates.
So, before that happens, spray it with a solution of baking soda, diluted 1 tablespoon per quart of warm water.
Repeat if a little comes back.
If you get a build up of baking soda on the dried fabric, remove by brushing and vacuuming if it all possible.
Rinse with clear water if you have to, but if you remove too much of the baking soda, the red discoloration will return.
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