i guess there are a number of reasons why plugs burn out.

in my case, it WAS because i was running too lean. i guess the air at the beach had something to do with it, but i was already inadvertently
running too lean to begin with.

i've richened up my mixture, made sure that there were no leaks and since then have not burned any plugs. the engine is running great.

the only thing is i crashed last week! ran my receiver battery down too low and just lost it. oh well, i now have an excuse to get the model tech twister, which i've been wanting since it came out.