Strange issue with stock

[mohsart]

I've noted for a while that the stock in PS doesn't match the actual stock, but thought that I forgot to update after a sale where the customer didn't use PS, so I've made a habit of checking the stock every month or so on items that I have only one or two of in stock.
But recently I got two orders from abroad (USA and Germany - in a new zone made by me for EU countries) and it seems that these orders don't affect the stock status.
Also, both were paid for with PayPal, which as with orders from abroad isn't too usual.

So I'm guessing that one of these factors is the culprit, are there any others who have seen something similar?

Edit: PS 1.2.4.0, default theme

/Mats