Probably not an issue, but you should check. If the port opened is something like 127.0.0.1:portnumber, then it's only bound to localhost, and only that local machine can access it. If no address is specified, then anyone with access to the server can access that service.
An easy way to see containers running is: docker ps, where you can look at forwarded ports.
Alternatively, you can use the nmap tool to scan your own server for exposed ports. nmap -A serverip does the slowest, but most indepth scan.