Clif
If it's new or known low pressure load brass I don't worry about it. I figure it's insignificant.
(Loose is a relative term)
If the primer is loose on reloaded brass of high pressure loads or unknown origin, I scrap it. (And reduce my load if it's mine)
(I recently talked with Stan Watson of the Lawton OK area and I believe he mentioned that primer pockets get blown at a pressure of about 73,000. 10,000 to 11,000 above most safe loads if I recall correctly.)