Theres is no "accident" and no "fall"! At all!
Of course it's not considered a fall! It's the natural way of a mans body. Yes, it can be caused by excessive thinking throughout the day, but it is also the way a body naturally releases a buildup of semen especially when the body was used to a release and now it didn't have one. It happens to everyone.
Regardless of the reason, it's not in your control at all when you are sleeping. Ignore it. It's totally nothing at all! Continue your beautiful new streak- you are still pure!
Grant
P.S. Obviously try your best to prevent it. Don't fantasize or excite yourself especially before going to sleep.
P.P.S. Just a question: If you are clean for 7 days why does your streak say much longer? You may want to update it to keep track...