I believe Hifiman QC issue rate is higher than typical. But they are likely still low. Most likely it is less than a handful per hundred. No one knows for sure.

If you think Sundara is so great, then do RMA. Or return and buy another; that way you can always return again if you encounter another issue.

On the other hand, if you can get similar value and sound in another brand/model, go for that. You have better peace of mind.