I have never seen one come off without some force, even if the stud itself was lubed prior to tightening, then dissassembled shortly thereafter (Doh!). I would have to wonder if it was fully seated in the first place.
Wait! I take that back! I saw this once when the tapered seat had been partially damaged by a bad job of drilling out a seized stud.
"Gritty" is bad. Smooth and stiff is good.
That is why sex on the beach is overrated.
1986 300E 5-Speed 240k mi.