python - Matplotlib can't give up old argument -

i made mistake in command matplotlib:

newline.=plot((x0,x1),(y0,y1),color='light grey') 

turns out there no "light grey". well, figured fix it:

newline.remove() newerline,=plot((x0,x1),(y0,y1),color='grey') 

but matplotlib returns same horrendously long error message, root problem being

exc = valueerror(u'to_rgb: invalid rgb arg "light grey"\ncould not convert string float: light grey',) 

that is, somehow, matplotlib thinks still trying plot "light grey". have tried few things around this, won't give light grey problem. it's offended or something. have ideas? pretty complex plot. don't want tear down , start again.

if matters, running python on enthought canopy 1.5.2, linux.