Yes; I am getting much the same writings about my locale encoding:
$ locale
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=
the warning is complaining about there being no en_US.utf8. The difference between what I have and what their warning about being the last five digits in that what I have is capitalized. I am assuming it doesn't really matter because everything seems to work correctly.
My web search with this new knowledge wasn't much help. Apparentlythere is a difference between UTF-8 and utf8 (UTF-8 being the official standard and utf8 being perl's version of the standard) but I could not find anything concerning utf8 vs UTF8. Oh! I just looked at it with new eyes and see that I was accidentally dropping the hyphen and that it is saying that perl's version isn't installed. So now I am sure it doesn't matter!