Possible Speedmaster 3861 Issue - Need Help.

[saudi]

I got a speedmaster 3861 a few days ago and everything seems fine, today i was playing with the chronograph and flipped the watch suddenly to view the caseback and the movement stopped entirely like i hacked the watch, when i stopped the chrono it started running on its own again. i flipped it again several times and the issue seems to only happen when the chronograph is running, is this normal or should i take it in?

Update: tried replicating the issue again after i made this post, i wound the watch fully and ran the chronograph and it was perfectly fine, does a low power reserve cause the issue mentioned above?