When I use the "BLUE PEN" for marking, I do soak the quilt for 30 minutes (minimum) in ice water in the washer. I just unload my ice bucket in the icemaker into the washer and let it soak. After the soak, I wash in cold water with Purex detergent (without bleach)
Either the section of quilt was exposed to heat in some fashion OR the pen bled thru to the batting.