To give some general information: I don’t think Storj software ever sends a ‘terminate’ signal to the storagenode. (That’s SIGTERM on *nix; CTRL_(CLOSE|LOGOFF|SHUTDOWN)_EVENT on Windows.) Even when there is an update, the existing process is shut down with an ‘interrupt’ signal (SIGINT) on *nix, or SERVICE_CONTROL_STOP on Windows.
To investigate further, we’ll probably need to look at your setup. What OS, are you using Docker, and if so do you have a watchtower container running?
An update of the storjlabs/storagenode image would not necessarily change the version of the storagenode binary, though. The bare image just knows how to download and run the right binary.
Check your watchtower logs- I’m betting it says something like “Stopping /storagenode” at around the same time.