I believe the instructions were to reconnect as soon as possible and complete the test in case of internet issues. Apparently you had no issue submitting the test and it was scored. If you didn't have any issues with taking the ID/picture etc it should be fine.
I believe the test site is designed to capture either occasional pictures or a video of you taking the test. Is it possible they're looking into any potential gaps? Yes but more likely, I think this is within the a normal timeframe for the test to be marked completed.
I wouldn't worry too much. If you want, you can write to the same email where the invite came from and explain the situation. I don't think you are alone when it comes to internet issues, I'm sure they've seen this a lot. You can also call them if you prefer.