Not sure whether it's a bug, but take a look yourself

As you can see, the two sliders are not aligned equally.
Can not reproduce it with the latest release.
This is a thing for me, too. I can confirm SHAD0WF4X's issue.
The error even occurs on the forms page, which I would assume to be the latest release. On local development I learned that the fewer steps you have on the range as a whole, the more obvious this misalignment becomes. (Example: a range that goes from 30 to 50 with steps of 10--meaning you have three steps on the whole range--has a bigger misalignment than the showcase range with 100 steps.)
Tested with FF 52.0.2 (32bit) and Chrome 56.0.2924.133 (64bit).
When did you test? (Windows 10 64bit here)

Probably related to https://github.com/Dogfalo/materialize/issues/4464
The moment I wrote my comment, on Win7 64bit.
Upon reading the original post again, I see that I have misunderstood the issue here. Just saw the mispositioned blob and thought, that this is my issue, my bad.
Alignment of the range itself is fine. The big thumb is misaligned, though.

Materialize's showcase

Lokal project
Maybe that's indeed a new issue... Sorry for mixing it up.
The PR should fix this. https://github.com/Dogfalo/materialize/pull/4466/files
It is just in the master branch and not yet available as release.
https://github.com/Dogfalo/materialize/releases
48 commits to master since this release
Please test the fix and close the issue if this solves your issue.
Like @DanielRuf mentioned, should be fixed with #4466