Answer: Yes it was.
Step-by-step explanation:
Shay's rebellion was an armed uprising against the government of the state of Massachusetts by mostly veterans of the American Revolution who had now become farmers. They were angry about having received little compensation after the war and of the method of debt collection being insisted on by creditors.
They burnt down government properties and attacked government courthouses and then attempted to steal weapons at a federal arsenal where they were defeated. They had been armed with an assortment of weapons as well.
This fits the definition of an insurrection as it involves a rebellion against the government by violent means and usually by armed people which is what was happening in this scenario.