I hesitate on this explanation in this specific case just because the reason that we think head tilting is cute in dogs is because we also do it - and IMO we also do it when we're remembering something successfully - so I'd check for it in non-domesticated animals (wolves) and in other mammals.
Our evolution has also been altered by dogs. We may have evolved the trait so that we could better communicate with them. Or we mimic them, a cultural thing.
I hesitate on this explanation in this specific case just because the reason that we think head tilting is cute in dogs is because we also do it - and IMO we also do it when we're remembering something successfully - so I'd check for it in non-domesticated animals (wolves) and in other mammals.