Bosnia has always been a separate cultural identity. I seem to recall the 1908 crisis when Austria-Hungary annexed it from the Turkish Empire. It was never politically in Serbia's sphere until 1917.
Having said that, this is a stupid move by the Bosnians, who should realize their real allies are the United States, not a group of opportunists who will sell them out when the going gets tough.
The Turks had already been driven from Bosnia-Hercegovina in the late 1870's, coinciding as it did with the Russian defeat of the Turks in their war of 1877-78. More than just a few Serbs took part in the uprisings which drove the Turks from Bosnia. What was their reward? The Congress of Berlin (1878), among other decisions, gave Bosnia-Hercegovina to the Austro-Hungarians to administer (that is, to swindle and strangle). Serbia, as an independent State, growing in strength and stability set a "bad" example for the people's around her (Afterall, freedomm is Empire's cancer). Austria was beside itself with hatred for Serbia and annexing Bosnia-Hercegovina was a statement directed against Serbia, as well as an attempt to resuscitate its empire, corrupt and dying at its core.