What could be the reason for intermittend "badtoken" errors when using MediaWiki::API's edit function?

In my script, sometimes I get that error. When I restart the script, it usually works.

I now inserted code to reconnect to my wiki in case a badtoken happens, but I'm wondering how I could debug the issus as it seems to be non-reproducible.

Update: The reconnect code helped. In my last run of updating 378 entries I received a bad token once. After reconnecting it worked.

my $retries= 3;
while ($retries--) {
    last if $mw->edit( {
        action => 'edit',
        title => $pagename,
        basetimestamp => $timestamp, # to avoid edit conflicts
        text => $text } );
    if ( 3 != $mw->{error}->{code} ) {
        warn "Don't know how to handle " . $mw->{error}->{details}. ' 
+('. $mw->{error}->{code} . ')';
        exit 1;
    }
    if (1 > $retries) {
        warn "No more retries. Giving up on " . $mw->{error}->{details
+}. ' ('. $mw->{error}->{code} . ')';
        exit 2;
    }
    warn "Reconnecting...\n" if $verbose;
    $mw->logout();
    $mw->login( { lgname => $settings->{USER}, lgpassword => $settings
+->{PASS} } )
      || die  $mw->{error}->{details}. ' ('. $mw->{error}->{code} . ')
+';
}
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