One thing that is important is to ensure the reviewer/referee(s) comments are addressed sufficiently in the submitted revised copy. I've seen manuscripts going from minor back to major revision or being rejected.
How long does it take to give a decision for a minor revision in mathematics?
Should I give a reminder to the editor?
Regarding your concerns, a reminder to the editor after 2 months might be reasonable. However, this is subjective as the review process varies from journal to journal, from field to field and circumstances (administrative and others).
As you've indicated, it could even be that the reviewer is busy.
PS: For me, I try to review minor revisions as quickly as I can, but at times I don't manage to and they pile up.
One more thing. Some journals share metrics of
- date manuscript was submitted
- indication of how long the review took: some even split info for 1st, 2nd, (3rd) reviews dateline/review period
- when the last revision was received, and
- how fast the publishing took (typically for online first (articles-in-press)
Some only share summary of when received, accepted and published like in this one.
If the (review) timeline are published, you can get a sense of how well yours is doing: too long, normal or pointer to abnormal!
I know you said it's a mathematics journal and from the time of your question, it's a reviewer (referee) and not two reviewers, it might still be worthwhile, for others sake, to refer to the typical workflow of a journal: What does the typical workflow of a journal look like? How should I interpret a particular submission status?
This might be worth noting: How to check how fast the review and publication process in a journal