1. XCoin as it was called at the time was based off of the Litecoin code base, which unbeknownst to the developers contained restrictions on the frequency and extent of adjustments which the network could apply to mining difficulty.
2. Because of these restrictions, and the popularity of mining the coin, the network produced a large number of blocks with the maximum allowable coins in each block. These went to whoever was mining and not to the developers only.
There were many people mining at the time who solved these blocks.
I am aware that Evan used code examples from Quark and Primecoin, but in the end he did fork Xcoin from the Litecoin codebase, which means in my view that the code changes he implemented
to correct the instamine (as described here : https://dashdot.io/alpha/?page_id=118), were indeed fixes to the Litecoin codebase.
Which means point 1. in my eyes is still correct.
I have difficulty believing the Litecoin fastmine only occurred due to the amount of people and hashrate, and not due to some difficulty bug in Litecoin's code base.
The same bug that then also showed up in Xcoin, when it forked from Litecoin.
Just because Charlie Lee states that there was no difficulty bug in Litecoin codebase (eventhough Litecoin got hit with a fastmine just like Dash), does not mean we have to believe this at face value.