I could easily see my bf reacting poorly to something along these lines, so yes - possibly you've accidentally triggered something. For my bf, I can try to compliment him and it only takes one 'poorly chosen' word for him to take it like a massive insult.
Looking at your post, perhaps it could have been the word smell? Just guessing here, of course, but the word 'smell' is usually used in a negative way - when you smell something, if someone smells, if there's 'a' smell it's usually not pleasant, whereas 'scent' is commonly viewed as positive. Considering she was bullied, perhaps it was as simple as that...
Of course you don't always string sentences together by considering each word you put in it carefully (how exhausting would that be

), so sometimes these things just happen. The fact that she came back after 15 minutes and apologized for her reaction is a positive though, at least it would be for me
Have you talked about it at all, after that?