No, there is absolutely a reason. The wrong passcode was entered too many times. That is the ONLY reason an iPhone is disabled for a time period. Once disabled it doesn’t tell the reason, because there is only one reason. The most common cause of this is carrying the phone in a pocket with the screen against one’s body; the body contact activates the passcode prompt and enters a random value.
A much less common, but possible reason is the screen is failing, and is randomly “tapping” the screen. This would be obvious, because you would see it doing things when you weren’t touching the screen. It’s commonly called “ghost touch”.