I think at 7 months you should be getting some worker die off for Pogonomyrmex. The 10 workers is over span of x days I presume. I'm more concerned you are not making enough workers to replace them. I'd expect more than 40 workers.
I also observed 4-5 deaths within 2-3 weeks in my Messor barbarus colony (~30 workers). If I am not mistaken, they were small so I thought they can be the first workers. I think Messor's nuptial flight is 2 months later than Pogonomyrmex, so Mushu's point might be valid for this colony as well. I saw 4-5 deaths but last time I counted the colony had a few more members than when I received them. So I am not alerted from this point of view.
Ok another 10 died. It's not the food, and there is nothing visiable wrong.
How is the water situation? Do they have access to drinking water and nest hydration?
On the other hand, I am very unsure about the hydration in the nest. So this is also my main concern about the deaths.
