I would say that I am 90% confident that it is the NDS of the axle that is slipping as I have to push that side forward when i release the QR and re-center. That said the issue always rears its head while on my morning commute and I fix it as quickly as possible so that I can continue. When re-centering I have never felt the DS position move but I will intentionally recreate the slip this evening and report back .