Bedroom ceiling shows water stains in one spot. 6 months ago had roof replaced due to hail damage. 1 week ago, had 6 inches of snow. Crawled up into attic above bedroom ceiling, saw small pile of snow. Roof above has 2 roof vents(louvre). What did the roofing contractor do wrong when installing the roof vents. Previous to hail damage, roof was the existing(new house, 10 years old) and never ran into this problem. What should I check into with regards to eliminating this "snow leakage" situation.