Do you season a cast iron waffle pan before using?
I see no reason that a cast iron waffle pan should be treated differently in regards to seasoning than other cast iron.  Since it won't be cooking anything with significant fat in it naturally, if anything it may be more important!  Seasoning is both for non-stick reason and  non-oxidizing reasons.  

Season it well on your own, then use it with some fat (of some kind) very lightly brushed on to keep it well. Only brushing right before use will keep one good likely, but would take a long, long time to naturally season since a large portion of the fat will immediately get used by the food.

Cast iron gets gummy if you either 1) season with a spray like Pam consistently or 2) don't cook your seasoning long enough and/or high enough.  Use a fat, bacon fat, would be great here and season away - properly.  In regards to seasoning, I recommend checking out this question, as its unneeded to replicate detailed information elsewhere in the site.