marker custom brush problem

[handrawn]

see the attached

when drawing with the marker custom brush and then zooming out this message appears

not seen it with airbrush or watercolor - just marker

its a real workflow interupter

going to try making up a brush to replace

meanwhile - what does this mean - I know its not new, is there a way to avoid it?

is it a bug?

I've tried resizing the brush [including the rectangle the brush is made from] - working at a different zoom range, neither seem to help

thanks