I had 2 cones of Connecting Threads do this. I contacted their customer service, told them what color number it was. They said that color was discontinued (I'm sure I had it for 6 or 7 years) but they offered to replace it with a similar color of my choice. That was about a year ago and I never followed up on it. Since I started using Sew Fine, I don't buy much CT anymore.

CT will replace but getting the problem stopped takes more cost then replacing. If the price goes up on the cone thread then probably the cones have improved.