Well am suprised that you are just witnessing this now because this is a pretty normal occurrence for play but not when I have loaded the site and started playing though, mine is always experience whenever I want to load it at first then after that successful verification it never pops up again. Last week was really worse and I had to simply change the browser of which I used in loading the site from chrome to Firefox browser.
Yes, I am used to always verifying it before I log in completely or if I am loading the page for the first time, but if I start playing, I don't normally experience it again, but it happened last week that I had to keep verifying it while I was staking my bet. After I started playing, it didn't come up, but as I was playing nonstop, they brought up the verification page, which I verified and continued the game, but after playing for some minutes, it popped up again. It continued like that till I stopped playing.
So, this is clearly nothing to be worried about, possibly it's just their way of trying to eliminate any and every form of ddos attacks, and the sweet thing actually is that, the verification is very simple and straightforward, some times, it even auto verifies by just clicking the verification box, and it's fast.
Ok, I thought am the only person experiencing and I was also thinking it could be caused by my IP.