At the start of the night springtrap will instantly bolt towards the player (I believe it only happens if you're within a chunk of him when he activates).
The phantom's also have this issue when they spawn in and similarly some vent animatronics get this issue when they enter and exit a vent though that one is less consistent.
For context the modpack isn't exactly small but none of them effect ai behaviour or could otherwise cause this (the bug has been prevalent since BEFORE additional mods were added but I know you guys like additional info on the used modpack.)