question re company accounting

The IGR SP took a significant hit when the announcement stated that costs of stripping the overburden prior to mining had increased the cost ratio of gold produced.

We lost our " one of the lowest cost gold producers" status.

Now company accounting isn't my strength, however I was taught that pre strip of the overburden was a capex item and not brought into production costs.

If this is correct, how did the pre strip costs undermine our cost of production by so much? Wouldnt the capex cost be amortised over the expedted gold return on the life of the mine.?

Can anyone explain this to me in plain terms?

Rgds
Angers