Express Cookie Handling - why does Connect call toLowerCase on all cookie names?

gistfile1.js

var express = require('express');
var app = express.createServer();
app.use(express.cookieParser());

app.get('/', function(req, res) {
    // Prints undefined
    process.stdout.write('req.cookies.RelayState = ' 
        + JSON.stringify(req.cookies.RelayState) + '\n');

    // Prints undefined
    process.stdout.write('req.cookies[\'RelayState\'] = ' 
        + JSON.stringify(req.cookies['RelayState']) + '\n');
    
    // Prints clever cookie
    process.stdout.write('req.cookies[\'relaystate\'] = ' 
        + JSON.stringify(req.cookies['relaystate']) + '\n');

    // Prints clevercookie
    process.stdout.write('req.cookies.relaystate = ' 
        + JSON.stringify(req.cookies.relaystate) + '\n');

    res.cookie('RelayState', 'clevercookie');
    res.send('hello world');

    process.stdout.write('----------------\n');
    process.stdout.write(JSON.stringify(req.cookies) + '\n');
    process.stdout.write('----------------\n');
});

app.listen(3000);