Thanks for the comments, I am actually shocked at how well it wears and how much I like it...
The bubble... it was serviced by Sinn in 2017 and had the bubble since. Again, it disappears when its warm. Apparently, the previous owner was in touch with Sinn and they said it's nothing to worry about and actually quite common - caused by a tiny air pocket left when re-filling the watch with oil after the service. It doesn't bother me at all and the next service is due in 2025, so... I'll just wear it for now.
Thanks for the comments, I am actually shocked at how well it wears and how much I like it...
The bubble... it was serviced by Sinn in 2017 and had the bubble since. Again, it disappears when its warm. Apparently, the previous owner was in touch with Sinn and they said it's nothing to worry about and actually quite common - caused by a tiny air pocket left when re-filling the watch with oil after the service. It doesn't bother me at all and the next service is due in 2025, so... I'll just wear it for now.