What happens if an omamori charm opens on its own?

I carry a love omamori charm on my phone case with the string tied around, but recently I was changing my case and realized the string loosened with the bag slightly open. I never opened it intentionally, and I only got a peek at the paper without the message. I also retied it with a simple knot. Still, I’m not sure if the charm is still useful or if there’s a meaning behind this? Should I dispose the charm or be worried or is it technically not fully opened since the string was still attached?