Yeah, the modern definition has changed to those who even live in "heated" areas. I bet our ancestors who hardly wore clothes has highest pit full of D levels haha.
Jokes aside, yes, that's quite low. You're fortunate (assuming there was no pain complaint from your wife) that she's not in pain yet. I was 9.63 in 2009 and I was all in pain, couldn't walk or lift my leg even by 2-3 cms. I had (and is still lasting somewhat) osteoporosis incurred due to low D levels. So yes, definitely supplement ASAP in large dose. 60K once a week is good, but I'd recommend a daily of 5K along with it too.
Back in February this year, I had around 28. Then I took a rigorous step and continued 15-20K daily for next 1 and half months and raised my level to a dreamy one, 62. Yes, and its been feeling good.
I've made quite a few Vit D related posts and threads, you can go check from my profile.
Best,
-P.