Since TWS doesn't run on Saturday - I'll assume that you checked your Friday account statement. Check TWS on Sunday after noon (EDT). It should show the stock positions. Occasionally, option assign/exercises may be delayed, but you should see them by Monday before the open.
Really? That's incredible. Is that policy in the contract? IB assumes that the trader/investor knows what they are doing and lets them carry any position that they have the margin for. (With a few exceptions - such as short stock buy ins and deliverable futures after the close out deadline). If they don't have the margin TWS will auto liquidate down to an acceptable margin level after giving the trader a short time to remedy the situation.
I checked my statement today (Sunday) and everything is ok, my options were excercised!! Thanks for your answers as they were correct!!!