Hi,
@Beth c , I don't want to worry you unduly, but, to be on the safe side, there's a rare condition called euglycaemic dka, which is where a person can be dka but not have high bg.
It sometimes comes about through fasting when ill, low carbing, infections.
If your +4 is way higher than it normally is, I'd get it checked out at emergency, even though bg is ok.
It'll probably be totally fine but you've been concerned enough about it to post about it, which suggests your +4 reading is out of the ordinary, and that alone rings a few alarm bells.
There was a thread a few months back where a poster reported a similar thing, although her ketone levels were much higher, she was reassured by keto people that she was fine, even though she'd gone from about 3 to 16 in a short period of time, and it turned out that, no, she wasn't fine, she had a kidney infection, so it was actually a major problem.
Docs aren't that aware of edka, so here's a link describing it:
www.edmcasereports.com/articles/endocrinology-diabetes-and-metabolism-case-reports/10.1530/EDM-17-0081