Actually, we were:

More than 30 security-related sources of radioactive elements were taken from Lebanon by a team from the International Atomic Energy Agency, the watchdog said.

An IAEA mission announced it had removed 36 Cobalt-60 sources with a combined radioactive of 3.500 curies. The agency said direct exposure to a single source was powerful enough to kill within minutes.

So where did it come from? Well, from this:

A Food Irradiator

A Food Irradiator

The irradiator in question was abandoned 10 years ago. No information where in Lebanon this took place or why it took more than 10 years to remove the radioactive material. The article does mention that it was used in the agriculture industry so it could have been in Bekaa Valley.

More Information: Atomic agency rescues ‘dirty bomb’ material

The International Atomic Energy Agency (IAEA) has repatriated dozens of Russian-made, highly radioactive sources that had been languishing unused in a Lebanese research institute for more than a decade.

The irradiator had previously been used to sterilize male Mediterranean fruit flies or medfly (Ceratitis capitata), with a view to controlling the medfly population and preventing crop damage by egg-laying females. But after the project ended, all the staff members who knew how to look after the radioactive equipment subsequently left the institute, leaving the cobalt-60 sources potentially insecure.