Steve, to add to Double's list, I'd say one thing I've learned in just about 20 years of running is that you sometimes have to sacrifice the short term for the benefit of the long term. In middle of a race, I don't think I would have made the same decision. However, given your history, it probably doesn't hurt to err on the side of caution at this point in time. After all, as you stated, you wouldn't have even run it if not for the free entry. If it's that unimportant to you, why risk the big races for it?
In other words, while I probably wouldn't have made the same decision in the heat of the battle, you probably made a better choice than I would have.