I watered the soil in the pot today. pH of the water was 6.4 going in. The runoff was 7.3
This may be attributed to the fact that I just repotted the seedling into a 5 gallon bucket and there is river rock lining the bottom. I did not rinse off the river rock, and this is the first time watering the plant in this container, so the reading may be skewed due to the river sludge washing off of the river rocks. I think the runoff pH will be a little more accurate after a few waterings.

As for the soil in the 5 Gallon bucket, it is a mixture I made:

60% Happy Frog Organic Potting Mix
15% Perlite
10% Building Sand
10% Worm Castings
5% Happy Frog All-Purpose 5-5-5 Pre-Mix Organic Fertilizer

I don't think the new soil is causing the curling, because the seedling was transplanted into the bucket from a fertilizer free germination soil mix and it was surrounding the roots a good deal during transplant. Also, the curling was occurring prior to transplant.