The answer to 'why is my drip edge curling shingles' is that the drip edge is not properly installed or secured, causing the shingles to curl up at the edges. This can happen if the drip edge is too short, not overlapped correctly, or not nailed down tightly enough.
Curling shingles can lead to leaks, water damage, and other roofing issues if not addressed. The drip edge plays a critical role in directing water away from the roof's edge, so it's important to ensure it's installed correctly.