Interesting.
I've gotten the odd weird colored egg, a few dark brown ones, one frosted blue.
There is a quail breeder in my area who has a line of quail that lay fairly bright blue eggs, some a blue base color with brown spots over them and some the usual beige with blue spots. From what they said both have proven out through subsequent generations.
If you never get another like it I wouldn't worry about a random odd ball egg, however if you get eggs like that consistently I would narrow down which hen it is and try to line breed and see if it's genetic just for curiosity's sake.
As long as the shell is normal, not thin or overly thick, lumpy or otherwise odd consistency then color shouldn't be any kind of indication of a problem. Eggs can be odd colored on odd eggs that were laid, my dark brown eggs all had thin/soft shells, and I've had dip-dyed looking eggs that were odd shapes. Again, if the egg is normal I wouldn't worry about a problem with the hen.
Pretty awesome looking little egg, I'd be interested to see if you get more.
Cheers,
Jessie