If milk spilled on a kitchen towel and dried out. Then later a person mistakenly used that towel to pick up a hot meat pot is there any problem with this?
If the milk was completely absorbed by the towel, and the towel is now dry (meaning that both the towel and the pot are dry), there is no problem.
The reason for this is that one keli doesn’t absorb from another when both are dry. Having been absorbed into the towel, the towel has the status of a keli, and will not affect the pot.
For sources on this matter, please see the comments below.