There is concern among Bosnian contacts that, if Iran feels things are going badly in Lebanon and that the war needs another front, it would take little to ignite Bosnia. It would not be hard to do and the international presence in Bosnia is greatly reduced. So is the intelligence capacity developed in the late 1990s.
Yes, Iran has assets in Bosnia. But attacking in Bosnia isn't so much a new front to threaten us as it is a threat to Europe that draws in Europeans to fight Iran in the Balkans and probably leads them to support our fight against Iran inside Iran itself.
I certainly can't rule out that Iran might think this is a good idea. If Iran opened up a Lebanon front to distract us from the nuclear issue, they may have just put their Hizbollah and Syrian allies at risk by drawing in the asset of the Israeli military to our side in the struggle against Iran. And to be fair, CNN will probably report a Bosnian front as a brilliant Iranian move.
But really, a Bosnia front isn't much of a threat in my opinion. A "new front" should stretch our assets and not add assets to our side.