Localhost hostname incorrect


I just installed pi-hole for the first time.
I decided to add a url from an ad to the black list. www.optimahg.com.au
for some reason my pi-hole device was showing up in iftop as the URL I banned. When i entered the domain of the banned URL + /admin into a web browser, it took me to my pihole admin page.
I am using my router as DHCP server, and the pi-hole device as DNS with static IP.
Restarting the router & pihole fixed the incorrect domain name.
I get just dont get what happened?
Is this post in the correct section and is there already a bug reported for this?
Screenshot from 2017-09-26 18-55-05




This is one of the only bugs in the released version, and is fixed in the next version.