The following code, a slight addition to test suite 
descriptions/labels-003.tex, when using ConTeXt from 20150904  and 
earlier works properly. Between that release and 20151004 something 
changed, and it fails with the labels shifted to reflect the temporarily 
narrowed text.

    \definelabel[MyLabel][way=bytext,text=OEPS]

    \starttext
         \setuplabel[MyLabel][alternative=intext]
         \MyLabel[labelname1] This is some text after \in[labelname1].
         \blank
         \MyLabel[labelname2] This is some text after \in[labelname2].
         \blank
         \setuplabel[MyLabel][alternative=inleft]
         \MyLabel[labelname1] This is some text after \in[labelname1].
         \blank
         \MyLabel[labelname2] This is some text after \in[labelname2].
         \blank
         \setuplabel[MyLabel][alternative=inright]
         \MyLabel[labelname1] This is some text after \in[labelname1].
         \blank
         \MyLabel[labelname2] This is some text after \in[labelname2].
         \blank
         \startnarrower
         \MyLabel[labelname1] This is some text after \in[labelname1].
         \blank
         \MyLabel[labelname2] This is some text after \in[labelname2].
         \stopnarrower
    \stoptext

Oeps indeed!
-- 
Rik