UPDATE FROM EARLIER REVIEW: Contracted company in October; new shingles installed within time frame promised (mid Nov). Work was fast and clean up was very good. Two windstorms resulted in missing shingles and rows of shingles blowing up to vertical. Initial response from company next day; replaced shingles and applied caulking to loose shingles. Said "All in good shape." Same day, high winds and more shingles rising. No other housess within several blocks had a problem. Company sent someone two days later, more checking, more shingles caulked, "everything looks OK." More high winds, same problem. Called company but this time it took almost two weeks to respond. Once it did however, came back twice to correct situation with Warranty Manager finally checking all shingles and applying caulking. He also checked back two months later and visually inspected interior of attic to ensure no problem.
No problems or leaks to date but each heavy rain or wind has us checking. My advice, after finding this is a not uncommon occurrence, have roof shingled in warm weather unless contractor applies additional adhesive.