Problem peeling last lot of liquid mask off

[barry]

As the title, I've just finished my first proper paint job. It went surprisingly smoothly until I took the last lot of mask off (using bob dively liquid mask). Instead of it peeling of nicely and cleanly I ended up picking bits of paint off where it hadn't peeled along the score I made with my knife.

Did I do something wrong or is the last lot always tricky due to the amount of paint over the score?

Barry