Yes, coincidence. People (probably) search tens of thousands of domain names each day. A certain number of those domains will end up being taken by someone else in short order simply due to coincidence.

It's the same coincidence that causes every really good name I come up with for a site to have been taken years ago. There are a lot of web developers out there!

>> taken years ago

this was taken the next day

I think you're seriously underestimating how much it would cost to run an operation like this and how little it would return them. As well as how quickly it would be discovered if done at a rate higher than coincidence.