Maybe this is a harbinger that something else [you could also say, "something more," "something further," "something bad," "something evil"] will happen.

Maybe this is a harbinger that something else will happen.
This morning, I found that someone had broken the mudguard over the rear tire of my bicycle.
I don't know whether this was accidental or deliberate.
I want to believe, however, that it wasn't malicious. [Formally, one should not begin a sentence with a conjunction such as but or and; casually, it's okay.]

何かよからぬ事が起きる前兆かもしれません。
今朝、自転車の後ろのタイヤの泥よけが壊されているのを発見しました。
わざとなのか、うっかりなのかはわかりません。
でも、悪意がないと信じたいです。

[残念です。気を付けて。]