If you want to check your frame's BB threads per Peter White's concerns, you could install the BB cups in the frame and then check the parallelism of the cup faces. Easier said than done but probably not impossible with nothing but a decent quality digital caliper. You could also place a metal ruler or something similar against each installed cup to magnify any parallelism errors.
Another way to check would be to install one cup only then insert the BB shell. It should be exactly centered in the hole on the other side. Try it on both sides to see if there is any noticable difference.
Or you could send the BB back to Phil and explain your concern. They could probably tell you if the grit in the bearings came from an 'improper installation' or if it came from external sources.
Finally, if you want to trade that Phil BB for a Shimano, I've got several smooth Shimano units I could trade. They're all English threading and in various lengths, UN51, UN52 and UN72, etc. Let me know...