Noticed this too and I've been living in Nevada long enough to know that Dugway doesn't do anything quietly without a reason. The restriction went up around the same time there were some odd lights reported out near Tooele county, which probably means nothing, or means everything depending on how you look at it.
What bugs me is the radius on it. Bigger than what you'd normally see for a routine test. I've watched the FAA NOTAM database on and off for years and this one felt different, the duration especially.
Anyone got the actual NOTAM number? I want to cross-reference the timing against some of the crop formation activity that was reported in Utah last spring. Probably a long shot but you never know what lines up when you start laying things on top of each other.
The government is very good at hiding things in plain sight. A flight restriction is boring enough that most people just scroll past it. Thats exactly the point I think.