Im sure its just the smell of your friction material getting very hot very quickly and burning off some of the dust and friction material that stunk. The smell ussually lingers around for a while because where your clutch is located there are only some small holes for visuall and clutch measurement. The smell could have just been slowly leaking out all day. The clutch probably felt different because you put some significant wear on it by slipping it that much. Clutch feel ussually very gradually degrades with use and when the time comes to replace it you'll notice antoher big differenece in clutch feel.
hope that helps