I just bought a cast iron waffle pan. I've seen conflicting advice about whether it should be seasoned. I have several old cast iron pans and my instinct would be to season it but I've also read that in a waffle pan the seasoning will get gummy and the waffles will stick to the pan. Some sites recommend just brushing the pan right before pouring the batter in. What are your thoughts?
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.
First, it's possible that you may not need to season the waffle pan because it's pre-seasoned. Most new cast iron you buy today from major US cooking stores comes that way. It could also be enameled and/or non-stick cast iron, in which case the same would apply.
If it's not pre-seasoned, you most certainly do want to season it. Waffle irons are notoriously sticky. I suggest that you take a look at the latest science around seasoning cast iron; might as well do it right if you're going to do it at all.
Based on personal experience using a civil-war era cast-iron waffle iron (yes, really), you'll also need to grease the pan with a lot of butter each time you use it. I suggest keeping a dish full of softened butter and a pastry brush next to the iron when making waffles.
No seasoning on any cast iron should ever get "gummy"; if it does, that means it was seasoned incorrectly. Given that some web pages I find recommend seasoning it with unsalted butter, I can guess what happened to those people.