Facebook(s fb) has asked the European Commission's antitrust watchdog to review its $19 billion takeover of the messaging service WhatsApp, according to sources of the Wall Street Journal and CNBC. The move may seem counterintuitive, but it would save Facebook the hassle of seeking regulatory approval in each European member state. European carriers in particular are reportedly worried that the deal – already green-lit by U.S. regulators -- would give Facebook too much leverage in the SMS-revenue-stealing mobile messaging market. Personally I think that market is in too much flux for a dominant position to be a sure thing just now, at least in Europe, but the concern is understandable.