Girlfriend hides text messages on lock screen?

Iv'e been with my girlfriend for almost a year now. We have never had any issues and I don't have any reasons not to trust her. Everything is going great but I have noticed that she uses this feature on her iPhone that hides text messages on the lock screen. So when she receives a text it just says "new message" until she unlocks her phone and goes into see it. Is this unusual at all? Why would anyone want to use that?
Girlfriend hides text messages on lock screen?
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