I wish I had Ironman Syndrome. I have "I'm sick of Ironman" syndrome. I'm just ready for the race to be here so I can do it, kick a** (well, hopefully kick it in 16:59:59) and get the training over with so I can lay on the couch and be a bloated, lazy, vegetable. That being said, tho, I'm worried that after the event I'll feel the need to train, train, train, when I really just need to rest, rest, rest. Gotta tell ya, right now I'm soooooo looking forward to sleeping in on a Saturday, not having weekends devoted to hours and hours of training, not smelling like sweat (even when cleaned and perfumed), and not washing dri-fit every 2 days. (wow- sorry so complainy. )

I know what you mean, tho. The constant need for more training. Good for you for taking the day off. You need to listen to your body and rest when it screams at you- it'll make it happy!
Sooooooo...yes- take the day off (and the next one, too) if you need to. You're not going to lose all your fitness if you rest, so JUST DO IT.