Someone recommended the Planet Waves Humidipak to keep in the case in order to keep the guitar humid and prevent the neck/fretboard from shrinking, and in turn preventing the frets from sticking out.
The roasted necks are less susceptible to changes in climate. But it's a good rule of thumb to not keep your guitar in too dry an environment. So if you're somewhere with no moisture (like my house with radiators in the winter ...) it's a good idea to get a humidifier in the room.
So I wouldn't rush out and buy a case humidifier unless you think you really need one.
That partly depends on where you live, where you are storing it. It's probably a good thing to go out and get a hygrometer to see if your primary storage location is up to keeping the L3 well humidified. If you're around 40% humidity, you're okay. Below that, I would think about a humidifier. This isn't just true of an L3. This is true of all guitars.
IMO looking up "warnings" or other people stories on the internet is like going to those self diagnosis sites and forums when you get sick or a symptom. There are too many urban myths, skewed fact, one offs and most def people who dont know too muchy about thier gear.
At the end of the day if you case it, take good care of it and not worry too much about what you read then you will be fine. I was worried for a good time about the neck moving more frequently on some of mine and after all the worry and research I found that they just will and it hasnt affected playability or quality at all.
My only point is address your worries minimally and have fun with it. BTW EBMM is the greatest customer service in the business. A full year is all you need for any tweaks once you buy new, for EBMM to do this and stand by the customer is unheard of to me. Thats insurance for the mind
Unfished necks like MM's are more susceptible, and the climates of some forummites are quite severe.
I had a new heating system installed in my house which led to drier/warmer conditions. A guitar that had a finished neck, and was built for me in the 80's developed fret sprout as a result. Wood is wood, and wood will want to dry out over it's life.
A humidifier in the case will not hurt at all and will not introduce excessive moisture either.
The ideal relative humidity for our guitars is 45%. I've been using the older style case humidifiers that require internal sponges be moistened with distilled water. Haven't had any issues using this method. The new humidifier packs don't need recharging like the sponge based older ones, you just toss them away and replace with new. I may switch to them before the Northeast winter heating season begins.
I've had a few guitars sprout their frets, and then had the fret ends re-dressed (some still under warranty...)
None of those have given me a problem since.
I think maintaining a healthy environment (humidifying if necessary ) is a good habit, but the one-time fix is a great additional set up...