Yarn bleed does occasionally happen, despite fully exhausted dye baths and extra rinsing and more rinsing, sometimes a yarn will either mark your fingers or bleed a little when wet.
Especially with darker colours… I’m looking at you black and blue!
Cool rinsing should sort out the problem.
If it persists or is more than a little, please get in contact!
If you are doing light and dark colour work then a swatch may be advisable