I was exposed to a fair amount of granite dust, without a respirator, during construction for about 45 min, is there a chance of developing silicosis?

Not long enough: Silicosis is scarring in the lung due to exposure to sliica over long periods of time such as sandblasters. Not for 45 minutes. Using a respirator mask and avoidance of dust filled environments is preventative. A one time 45 minute exposure is not a concern to develop silicosis. The who http://www.Who.Int/peh/occupational_health/ochweb/oshpages/oshdocuments/factsheets/silicosis.Htm is informative.