is it only happening at idle?
My car does the same from brand new (3 mths old).
Check your idle. If it is in the 500-600 rpm range then get it bumped upto 750rpm or so.
The misfire isn't a misfire. It will be the dual mass flywheel chattering!
I took mine to Nissan & they couldn't find diddly squat wrong, no fault codes logged. I then took it to Nismopete, a mechanic in Sydney who diagnosed the 'problem'.
Nissan Aus used to replace the clutch/flywheel here in the early days becused they did'nt know what the problem was, but now they just bump up the idle to around 750rpm.
Hope this helps