Yeah my Lincoln Premier, has just started doing this to me only yesterday, it's not cocking correctly, as there is no internal movement when you pull the trigger (like the saftey is still on as described by bigdog), its defo not a primer problem as no mark on the cartridge/primer either, its not the barrel selector either
opening and closing again seems to fix it, I shot about 75 yesterday and it happened about 3 times within my last 20 shots,
After cleaning it last night I did about 20 test fires with those empty/blank cartridges you use for storing your gun and prolonging the life of your spings etc (cant remember correct name for them) anyway it worked 100%, so think it's as it gets warm it gets a bit gunked from the excess oil from the incorrect storage for the last few months because I have been storing it barrels up, have been told to store barrels down as any excess oil after cleaning will run into the stock and the trigger mechanisms when stored barrels up, common sense really and so obvious when you think about it, it just never occured to me :-(
I think it will need to go in the shop for an internal clean to get it back 100%, and its still under warranty as only new in March
other than that its been a great gun so far, but I'm still a total newbie and learning every day