Hey guys,
I just wanted to update the thread. I took my watch to my local Omega boutique in Costa Mesa, CA and asked if they could demagnetize it. They said that the watch was indeed magnetized and then demagnetized it in a couple minutes. Then, I visited the watchmaker they referred me to right after. He tested how my watch was running and said that it was now running at -8 to -9 seconds. He said it was running fine and that I don't need to worry about anything. I think -9 seconds is reasonable for a 42 year old 861 movement, so I'm just going to forget about it and make sure I keep it away from magnets in the future.