Changing to another DNS resolver returned the new one, though. So I think you just have to wait for the change to propagate worldwide. Or, if you’re impatient, use another DNS resolver on your machine, like 8.8.8.8 (Google).
Interestingly, it was my local machine from which I did the nslookup the first time. However, doing the same nslookup on the same machine just now did return my old IP address.
I guess I’ll wait… Normally (lately) DNS propagation has been really fast for me, but not this time.