From what the pros tell me: Spark Plug blowing out of the hole is usually a result of loose torque (not tightened enough).
With time, the spark plug works its way out and kaboooom.
If you decide to fix this, research
Helicoil (basically a spring) vs
Timesert (a full insert).
Most pros recommend Timesert.
-----------
You may want to visit this thread FYI. Also, see the attached pic. Honda V6 cylinder head has some12 threads, not like some other makers engine with only 4 threads ---> spark plug blowing out.
So in the case of Honda V6, you can see the spark plug (which has about 14 threads) is fully seated in the thread. So to have the spark plug blowing out, my guess is a spark plug loose to start with.
DIY: 2007 Honda Odyssey Spark Plug @ 40K miles
http://www.odyclub.com/forums/showthread.php?s=&threadid=132134