It would have been great if this info could be posted on the addon's webpage - order this via CC and not paypal.
We couldn't possibly do that, because it only happens at entirely random times and, most of the time, users can order KIAH with PayPal just fine and, even the PayPal reaction to the problem seems to be random: sometimes the order just go through after a couple of days, sometimes gets canceled.
We only noticed it seems to happen more often during sales, but it's impossible to say if it' just because during sales the simple increase in orders raise the statistical chance of this happening, or because during Black Friday, PayPal changes the configuration of their filters or, possibly, hire additional staff which is not very well trained to handle this...everything is possible and, as I've said, PayPal won't even speak with us about this.
But most of the time, PayPal works, and it's used by lots of people, so we cannot possibly advise against using PayPal in general, and it would look suspicious if we suggested to buy *again* with a different method, especially in case PayPal decide to let the Pending order to to through, which DOES happen too.