Well, it's not a real bug. However, this refresh event (Events.Refresh) fired by GridView definitely deserves it's place in API documentation. It's very (very!) useful event, because it's the only way I found so far to get notified that:
1) Data has been loaded and
2) Store is ready and,
3) View is ready.
I can use it, for example, to apply custom styles to grid rows or set some initial grid selection (I've done keeping selection between pages). Or, if it's a part of some hidden internal GXT API and I shouldn't use it anyway, there should be another way to achieve that goals.