I have no iron at all!
I don't even remember last time I ran out of iron, I had completely forgotten that was a thing. Thanks for spotting it.
Yeah, I had a similar case in my game. Hired a bard Horseman, and after a few battles, I started to wonder why it wasn't healing up anymore. Took me a long time to remember "OOHH! I have no horses!". Rarely now do I not have any spare resources, and also the fact that I knew I had horses like 5-6 tiles away from my capital that I was planning to settle but just hadn't gotten around to yet, my brain just assumed they were already connected.