Is there a reason for having a few options using underscores while all others are camel cased?

The underscored options I've found are:

• Server.options.auto_reconnect
• Db.options.native_parser
• MongoClient.options.native_parser
• ReplSet.options.rs_name

It's not such a big deal, but fixing it would be quite easy. If you think it's worth, I'm willing to write a patch for it.