Shares reported by pooled mining less than local count

[tani171]

Well, this explains a lot. Was wondering why I couldn't post.

GUIMiner's share count is not matching what BTC Guild is reporting.

For one of my workers I have 169 shares, and 2 stales. Reported as 169 (2). GUIMiner is reporting 173 (6), so that's at least 4 shares short. More so, I've done some mining before using GUIMiner and so I should have more than 173 shares submitted.

The same for another worker. I have 393 shares accepted, 7 stale (invalid) but BTC Guild reports 376 (9).

So is GUIMiner counting incorrectly? Or am I being jacked by the pool owner?