A respectable journal with high standards recently published a (mathematical) article. I care about the topic deeply, so I had a look at the paper. In several parts, it is poorly written (the authors are not native speakers, but I'm unsure whether they are students). In my opinion, the results are definitely not substantial enough for the given journal (the same journal has both rejected and accepted my work). However, after fixing language errors, it would have been an OK publication for a lower-tier journal (in my opinion).
The following two facts raise my suspicions even more. First, the authors of the paper are from country X, and the paper was communicated by a person from country X as well. Further, the whole process (from "received" to "received in revised form") is only 3 months, and I wonder if enough time has been given to review the paper.
I know "bad papers" appear in "bad journals", and with these I don't bother. This time I'm wondering though: should I let anyone know, or just move on?