BlueJellyBean

Hello, this is more of a question then a topic, but i didn't know where to ask so I'm just gonna post it here So today some workers came to my house and started cutting metal bars with a large machine. After they were done, there was a lot of metal powder on the ground, so I grabbed 2 magnets shaped like a ball and started gathering the powder, and then put it in a container. However there was still some powder on my magnets. It stayed there for 3~6 hours. I used water to try and remove it but it didn't work. So I left it to dry for an hour or two, when I came back I managed to remove it. And when I did. To my surprise the magnetic field of the magnets was much larger, the 2 magnets would act crazy if they're 20cm apart(they would either push each other, slowly come closer, or start spinning randomly) they never did that before. And also they had to be at least 5cm apart to react to each other, and 20cm? How?! So the question is: why did the magnetic field become bigger?