This is a gray area.
In general, if your edit address everything in the post, then it is not "Too Minor". And I think that your post hit most of the major problems with this post. So by that definition, I don't think your edit was too minor. There was a couple of other grammatical changes, but nothing worth rejecting an edit over.
However, the problem is the definition of "minor". Some reviewers tend to judge a minor edit as only changing a few things, rather than the preferred definition of fixing (most) everything that is wrong. When you make small edits like this, you need to accept that your edits might be rejected more frequently.
I think you might have just gotten unlucky here in that you ran into 3 reviewers who don't understand the community's definition of "too minor" when it comes to edits.
All of this being said, the tag edit is the key change here. Without it, or if it wasn't a good tag to have on this post, I probably wouldn't have considered making this edit. "in C#" in the title isn't bad (in fact, including a tag in a sentence like that is one of the few cases where tags in titles are acceptable"). And "thanks" on its own isn't inherently bad enough to suggest as an edit on its own. But since the tag edit was important, it made the other changes important enough to make.