Threads Deep Enough?

So I had a guy true a wheel for me. it looks good and it is strait but some of the spokes are a little low in the nipple. I am worried if I hit a large pot hole it could collapse the wheel. Is this a legit concern? Some of the spokes cant be more than a few threads deep into the nipple. Should I be worried and have it done again?
Thanks
Patrick-

Hard to tell a little low from a lotta low. A pic might help....