This is just embarrassing. I am constructing a file directory composed of bits of strings so that it's something like:
my $base_directory = "/here/is/my/directory;
my $folder = "MyFolder";
my $file_name = "SomeFile.file";
my $full_path = $base_directory . $folder . $file_name;
And I omitted the full path slashes between the base directory, folder and file name and got,
$full_path = "/here/is/my/directoryMyFolderSomeFile.file"
Instead of what I wanted which was
$full_path = /here/is/my/directory/MyFolder/SomeFile.file"
I was so wrapped up in applying this new file size operator, that I didn't check to see what I was actually getting in composing the full path.
Applying -f to see if I was actually getting a file exposed the whole mess right away.
Something like this fixed the problem:
$full_path = "$base_directory/$folder/$file_name";
Sorry to bother people with this one.