Love Monte 4s. One of my favorite PCs. One thing that may take into account some of what the other guys are talking about with distribution storage RHs, etc, could be solved by going to another reliable source for this next purchase, and to keep it to one box in the event that you find a similar experience which could indicate the humidity issue is on your end.
I usually smoke one ROTT as a baseline for each box I buy and I've not had any issues. Shipping time is of course another variable there though. Montes are pushed out the door though so you might have just been unlucky.
I do introduce them slowly like jfire mentioned, but in a matter of months not years. I also store 97% of mine open in my wineador and not in their boxes. I know a lot of guys would rather keep them boxed, but the drawer set up I have doesn't leave a ton of room for boxes and over half my stash is CC... Oh, I usually keep mine a bit lower than 65 as well, as I prefer a dryer smoke. More like 61-63rh.