I think much of the stigma on job hopping comes from it really having a lot of advantages for a worker who is up for it (it gets progressively harder to deal with the first 6 months in a new job the longer you are stably employed and the more specialized you get.)

If I felt I had an external justification to explain a hop and I had doubts about my employer, I would look immediately for a job filtering for ones that I would actually want to keep for 3-4 years. If a new employer accepts you and you actually stay a few years, I would consider a future employer that had an issue with your resume rather odd. While sticking it out at an employer that you feel uncertain about can leave you in a worse place with the wrong timing.