1869 12c Scott 117 No Sign Of Grill

I just received a modest stamp collection of mostly affordable classic US material (best items are probably a very faulty Scott 70d and nice used 120 and 121), but it also had this. It appears at first glance to be a run of the mill used 117, but turn it over and there's absolutely zero sign of a grill. Sites like theswedishtiger.com are telling me missing grill errors exist on the 1869s and can be very expensive, and there is also a rare 1875 reissue with no grills. All the other pictorials in this collection have obvious grills. I don't want to sell it without knowing what it is, so please take a look below and educate me.