Contact them directly and maybe that will ease your worries, but based on the amount of servers and DCs they have been adding to their network recently, I wouldn't worry about it.
Our business hosts off of AWS and two other hosting providers, in addition to utilizing Cloudkick, Sendgrid, Geckoboard, Dynect, and Chartbeat.
It is my job every day to "worry" about how PAAS providers might not be able to deliver services to my business.
We're now in contact with Cloudflare to see how we might progress, but understand that a random posting that says "don't worry" without any substantial background makes me worry.
I contacted them directly and they were exceptionally (and intentionally) vague.
I asked them how on earth they could provide a service like that at such a low cost, and why there were no bandwidth limits in any of the plans (bandwidth isn't free).
Their answer was that they couldn't tell me the answers to my questions as it would reveal business secrets or something to that effect.
At the rate of start-ups spooling up and shutting down these days, I wouldn't bet my site's DNS on a company that appears to have no sustainable business model, and is deliberately withholding information that I'd use to judge if they'll be around in 6 months time.
