Welcome back
This might not apply here, and there still might be an issue, but it's not uncommon for the rear end to be a bit off from one side to the other without there being an actual problem behind it. It happened loads on the old mk4 platform; one rear wheel poking 10mm more than the other, 15mm discrepancy in ride height etc. Some cars just didn't sit properly whatever you tried.
I haven't seen or heard much of the same with the mk5, which stands to reason as it's a completely different (and loads better) rear suspension setup. But I've read about one car on a US forum like this.
Hopefully though after a quick check there will be an obvious reason that can be sorted. Let's hope everything is as straight as it should be.