The answer to 'why is my ridge vent curling shingles' is that improper installation or damage to the ridge vent can cause the shingles around it to curl. This happens when the ridge vent is not properly sealed or secured, allowing air and moisture to get underneath the shingles and lift them up. Over time, the repeated expansion and contraction of the shingles due to temperature changes can lead to curling and cracking.
To fix this issue, you may need to have a professional roofer inspect the ridge vent and make any necessary repairs or adjustments. This could include re-sealing the vent, replacing damaged shingles, or even completely replacing the ridge vent if it is beyond repair. Attempting DIY repairs on a ridge vent can be risky and may lead to further damage, so it's generally best to call in a professional roofer for this type of repair.