Coinbase and "Fraud"?

Has anyone else gotten a transaction canceled from coinbase.com due to "potential fraud"?

I put through a buy transaction for 1BTC at $167. That went through with no problem, with the exception that it took a week to actually complete because they took so long to withdraw the money.

When it went down, I put in an order for 2BTC at $67. This transaction, which was to have completed in just a few hours, was just canceled:

Hi,

Unfortunately, we have decided to cancel this order because it appears to be high risk. We do not send out any bitcoins on high risk transactions, and your bank account will not be charged.

Please understand that we do this to keep the community safe and avoid fraudulent transactions. Apologies if you are one of the good users who gets caught up in this preventitive measure - we don't get it right 100% of the time, but we need to be cautious when it comes to preventing fraud.

You may have more luck trying again in a few weeks. Best of luck and thank you for trying Coinbase.

Kind regards,
The Coinbase Team

To me, this is highly suspicious. It smacks of potential fraud on THEIR side:

1 - They're more than happy to put through high buy orders when it takes a week to get the money and it can go down.
2 - They don't put through a transaction when the price I bought at is roughly half of the current price. I suspect they're waiting to buy coins and it doesn't work well for them always so they cancel the transactions that don't work in their favour.
3 - They're potentially over-subscribed and so are cherry-picking (at random? non-randomly?) which transactions to fulfill or not.

They haven't charged me, and say they're not going to charge me, so right now there's no actual malfeasance. However, I am highly suspicious of them now.

Has anyone else had similar experiences or am I just being too paranoid?