Thanks for the comment David.
I heard that noise too when listening back, though not while playing. Must have been something outside - traffic can be very audible in this church which is too near the road for comfort. In fact I had to redo one of these because some brat with a power exhaust roared all over my closing bar and the silence after it
Walther was a very accomplished composer, as witness the half dozen pieces I have recorded. I know only two tiny chorales by Vetter so I can't really compare the two. But I'd say he too was a good composer with a strong voice. I'll try to find more of him. This little piece. not even one page long, took me surprisingly long to get right.