Period close reconciliation discrepancy analysis

Have 2 questions-1. 

Using Average costing method.

Specific purchased item received during the inventory period at different PO price which means the average unit cost is getting updated with each transaction.

Period close discrepancy report shows discrepancy because

Accounted value is based on actual transaction cost (PO price) which is different than on hand value (based on inventory qty*Average cost).

Does this mean that discrepancy report will show discrepancy if transaction cost (by transaction) varies?

2.

If we have discrepancy in a closed period will it roll forward to future periods? We have discrepancy in MAY-13 and see the same discrepancy when we run the report in simulation ode for JUN-13.