aqUtils.Delay() vs Delay()

I have upgraded to TC 15.80 with python. I have encountered one  issue that puzzles me.

Historically, in our scripts, we have used Delay(time in millsecs) when needing to have a hard pause in our script. We did NOT use aqUtils.Delay(##), just plain Delay(##). This has always worked.

Delay(1000)  # we used this to pause for 1 second

aqUtils.Delay(1000)  # we did not use this

Now I am getting error "name 'Delay' is not defined" since upgrading to TC 15.80. If I add import Sys or import aqUtils then the Delay starts working again, even though I did not change the Delay call to aqUtils.Delay(##). 

from tc import Sys
from tc import aqUtils

def main():
    Delay(1000)  # this works if I add either of the above imports

    aqUtils.Delay(1000)    # regardless, should I be using this with import aqUtils?

So, what is proper? Should I have been using aqUtils.Delay(##) all of these years?