It didn't look like a "flame". It looked more like a valid point that your post appeared to misuse the term "proofread".
Unless you wrote the article or are responsible for editing it, you would not be proofreading it. IF, however, you meant you want to go back and read it closer that would not necessarily be "proofreading".
Proofreading is reading an item to find errors, as in pre-production "proofs" or "galley proofs" before publication.
Now, granted the other poster could have been a bit more gentle with the reproach, it isn't necessarily a "flame" to ask it that roughly.
And, according to common parlance, you were probably not going to be "proof reading" it unless you were doing so to ensure it was ready for production/publication.