I think you will find that if you spray starch both top and backing heavily, this will eliminate the little tucks. The problem is probably not with the walking foot, but rather with the fabric stretching a tiny bit with the sewing. Starching will stabilize the fabric so it doesn't stretch.
My preference is to starch before creating the quilt sandwich. I use spray starch on the top and a 1:1 solution of Sta-Flo liquid laundry starch and water on the backing fabric. I saturate the backing fabric with the starch solution (using a large wall painting brush to apply), toss in dryer, then iron with steam.
If you already have the quilt sandwich basted, spray starching both top and backing will still help prevent tuckers.