Does this one-line text-based terrain generator go against standards?
What does THE standard say about imports :


  Imports are always put at the top of the file, just after any module comments and docstrings, and before module globals and constants.


What else could easily be improved in your code ?


_ is a usual name for variable whose value is not going to be used.
you do not need to create a list : you can use generator expressions by getting rid of brackets.
you can get rid of the duplicated prefix and suffix in the different choices.
in Python 2.*, you do not need parenthesis to call print.


Your code would become :

from random import choice
from time import sleep
print ''.join('\033[7;' + choice(['1;32','32','1;33','34']) + 'm  \033[0m' for _ in range(40))
sleep(0.5)