I would wait for the formal scores and interpretive narrative, even if the evaluator seemed confident. While an experienced assessor can get a pretty clear picture during and immediately on completion of the testing itself, you will likely receive a more thoughtful and comprehensive understanding of her results when the scores are explained in context.
I would guess that she probably was not estimating based on the raw scores, but looking up scaled scores for subtests during the testing process (easy enough to do since they're in the same manual used to administer the test, and there are a few moments where the examiner just waits for the student to complete a task independently). That isn't the full process for calculating IQ scores, and, of course, a conscientious evaluator might like to go back and make sure everything is scored and recorded accurately, which is why she might be cautious giving more specifics.
