¿"Lista de argumentos demasiado larga" con solo 2 argumentos?

I'm debugging someone else's code, and I've run into a situation I wouldn't know how to produce if I tried to code it deliberately. It's coming from a very large Bash script, being run by Bash 4.1.2 on a CentOS 6 box. While the overall program is gigantic, the error consistently occurs in the following function:

get_las() {
    echo "Getting LAS..."
    pushd ${ferret_workdir} >& /dev/null
    #Download:
    if [ ! -e ${las_dist_file} ] || ((force_install)) ; then
        echo "Don't see LAS tar file ${las_dist_file}"
        echo "Downloading LAS from ${las_dist_file} -to-> $(pwd)/${las_dist_file}"

        echo "wget -O '${las_dist_file}' '${las_tar_url}'"
        wget -O "${las_dist_file}" "${las_tar_url}"
        [ $? != 0 ] && echo " ERROR: Could not download LAS:${las_dist_file}" && popd >/dev/null && checked_done 1
    fi
    popd >& /dev/null
    return 0
}

If I allow the script to run from scratch in a pristine environment, when this section is reached it will spit out the following error and die:

Don't see LAS tar file las-esg-v7.3.9.tar.gz
Downloading LAS from las-esg-v7.3.9.tar.gz -to-> /usr/local/src/esgf/workbench/esg/ferret/7.3.9/las-esg-v7.3.9.tar.gz
wget -O 'las-esg-v7.3.9.tar.gz' 'ftp://ftp.pmel.noaa.gov/pub/las/las-esg-v7.3.9.tar.gz'
/usr/local/bin/esg-product-server: line 428: /usr/bin/wget: Argument list too long
 ERROR: Could not download LAS:las-esg-v7.3.9.tar.gz

Note that I even have a debug echo in there to prove that the arguments are only two small strings.

If I let the program error out at the point above and then immediately re-run it from the same expect script, with the only change being that it has already completed all the stages prior to this one and is detecting that and skipping them, this section will execute normally with no error. This behavior is 100% reproducible on my test box -- if I purge all traces that running the code leaves, the first run thereafter bombs out at this point, and subsequent runs will be fine.

The only thing I can think is that I've run into some obscure bug in Bash itself that is somehow causing it to leak MAX_ARG_PAGES memory invisibly, but I can't think of even any theoretical ways to make this happen, so I'm asking here.

What the heck is going on and how do I make it stop (without extreme measures like recompiling the kernel to just throw more memory at it)?

Actualizar: To answer a question in the comments, line 428 is

wget -O "${las_dist_file}" "${las_tar_url}"