This is about Mazda rather than the Miata.  I own two Mazdas, a Mazda6
and a Mazda3.  Hindsite tells me I should have varied brand names a
bit.  But this is how things turned out.  The popular mazdaXforums
websites are more geared towards fandom than actual technical issues.
So this is the best place I could think to ask a few questions.  I
hope you don't mind the semiOT post.

My Mazda6 is the 6-cyl 5-speed automatic version.  It's had three
CEL lights in the past year (the last one was four or five
months ago).  The dealership took the car the first two times and
gave me a rental.  They reset the CEL and did a lot of ignition
work the first time (new plugs, somethind else - I can dig up
the WO if it's of value).  The second time, they reset the CEL
and gave a story about firmware.  The third time, they didn't
take the car at all and said the CEL would go away.  It did.
The first two CELs were misfires.  The third probably was too,
although the code was never read.

My Mazda3 is the 2.3L 5-speed manual version.  It had a CEL go off
last night.  I've put about 20 miles on it since.  I haven't called
the dealer yet.

Between two Mazda cars, I've had 4 CEL lights.  Alright, now the
questions.

Independently of Mazda's bullshit, what's going on?

Is it some quality issue with Mazda?  Maybe the engines
just aren't put together well.  The 6-cylinder is the American
designed and built variety (ie Ford).  I'm not sure about the
4-cylinder.  Or is the computer too sensitive?  Perhaps misfires
aren't as uncommon as people think.  Could it be that it just
reports everything?

Are my driving habits to blame?  I did hit the rev limiter on
the Mazda6.  The tiptronics absolutely sucks on it.  Sometimes
it would delay my shift and continue in a lower gear until
the RPM went above redline for a second.  I experimented and
stopped using tiptronics over about a month.  I've never hit
the rev limiter on the Mazda3.  I rarely shift aggressively.
I did so three days ago merging with interstate traffic.
Crazy holiday shopping patterns led to the low speed lane
doing 5 mph and the next lane over doing 40, so the car
had to scoot.

Will I do damage driving the car now that it has a CEL warning?  
It's a bad time to bring it into the dealership.  I'm too dependent
on the car right now and can't spare the time from work.

Can I actually detect a misfire?  What symptoms do they show?
(Besides a CEL obviously :-)  

The Mazda6's strings of misfires stopped - or at least the
misfires have disappeared for the last four months.  Could the
misfire be related to engine break-in?  It has 15,000 miles
on it.  (The Mazda3 has 5000 miles)

I'm skeptical of the dealership's claims right now.  I work
in IT and I hear bullshit stories all the time to soothe the
client while not really addressing the issue.  Unfortunately,
I don't know nearly as much about cars as I do about computers.
I've lurked here forever and have seen some excellent advice
and help offered.  If you want to send some help my way, I'd
appreciate it.

Thanks.