Al Qaeda in Iran. Why?

According to some reports, some members of Al-Qaeda have escaped Afghanistan and are hiding in Iran, it’s suggested, with the approval of supportive Iranians. My question would be, why would this occur?

Al-Qaeda and their former protectors, the Taliban, are both really fanatical Sunni groups, for whom in many ways, Shi’ites are worse people and more dangerous than non-Muslims. Iran is a mainly Shi’ite country, who have no use for Sunni Islam and hated the Taliban, which persecuted Afghan Shi’ites and killed Iranian diplomats. So, what’s going on here? I don’t really understand.

“Supportive Iranians”. According to the CIA, Iran is 10% Sunni.
http://www.cia.gov/cia/publications/factbook/geos/ir.html