The top of the the rhizome should actually be open to the sun. Some iris are more able to handle mulch than others, just harder, so you might get away with just a thin layer of compost. Did you trim the foliage a bit? I always do that when I transplant. Now, I was assuming these are bearded iris. Japanese, Siberian, or some other variety can be mulched.

I didn’t trim, but I will do that, I was wondering if I should. I am presuming they are bearded, I just moved here in the winter so I haven’t actually seen them bloom yet. They are large like a bearded iris though.

My bed is sloped so it should actually be kinda easy to expose the rhizomes as long as moving them a little won’t totally shock them after the transplant? I’ve never had irises before.

Bearded iris are so easy, you should be fine. I have had a few bearded iris be finicky, but generally they multiply fast. They have to regrow roots though, and takes them a while to do that usually. When I transplant in summer-mid June through July is what the iris society does here-some will look pretty dried up, some even might look dead. In September/October they green up nicely though.