4% seems almost refreshingly low compared to some other places, but I'm not sure how they're figuring it. The difference is US$15.11, which is almost 4.8% of $316.31 and even if they are erroneously calculating 4% after the markup $15.11 is still ~4.6% of $331.42. Even if they're using an exchange rate from yesterday or Friday, there's not a significant difference, you have to go back like a week on the XE graph for it to be 4% of the non-marked-up amount. Unless I'm the one mathing the math wrong...

Anyway my main novelty in posting this is that I forget whether I have seen the "defer" vs. "immediate" phraseology before.