No, you don't need to, because the tea bad would be rolled, so their would be good air circulation to begin with.
I wouldn't use a spring
mod, because that metal is gonna get reallly hot and either help burn the cart, or the tea bag. I would go with the Lipton Pyramid Tea Bags, they're nylon, so they will not burn, they're re-usable, and the work perfectly! IMO.