In your code at line 27 I see:

            if ($@){
                "Couldn't get location : $place\n";  ### LINE 27
            }else{
                ($long, $lat) = @{ $response->{Point}{coordinates} };
            }
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What is the purpose of defining a nice error message string and then doing absolutely nothing with it? That's the "Useless use of..." something. Did you mean to print this string?

Do you think it's a problem...

Do you think it's a problem? The 'error' you cite is not an error per se, but a warning (see warnings module). Your code will still compile and run when this warning is being generated and you are free to ignore it if you wish, but it's usually a strong signal that something's wrong, as in this case: no  print() call.