Brown rings in the hibernating kefir; are the grains still good?

I had stored my kefir grains in the back of the fridge in a jar of milk. Although, I intended it for 2 weeks max, I think I went over 3 weeks. The kefir had rings of brown on its surface. I rinsed the grains. They look like they usually do. I have now soaked them in water in the fridge overnight in an open glass bowl. Do you think they are still good? Anything else I should do to help them? What happens to the grains if stored too long? Do they become contaminated? Do they die? What does the brown discharge mean?

Thank you!