I don't think this is a healthy level of suspicion to levy against an otherwise correct summary. If you think their comment would be improved with a citation then simply adding it would be good - cited comments are relatively common here but not mandatory and generally not how people communicate.

In what way could you possibly interpret that writing as "strange"? That was an excellent, straightforward response.

Some might find ending every last word in every sentence with an arbitrary number a bit strange.

If I had to guess it seems like they meant to cite their sources, but forgot to do so.