3yo focusing on patterns

[Booboostoo]

Is this a normal developmental stage or something that we should keep an eye on? DD is 3yo and for the past couple of weeks she is focusing a lot on patterns and behaviours shaped around patters. For example, in the living room there are alternate white and grey tiles and she makes a point of only ever stepping on the grey ones. In the dining room there is a dark wood border and she never steps on the dark wood border, she says that if we step on it it will explode. Is this just normal imaginative play or a sign of something else?

Sounds fairly normal to me. As a species, we seek out patterns even where none really exist, and it sounds as if she's doing that. Ever heard of, "Step on a crack, break your mother's back"?

Thanks. My family has a history of OCD and I suppose that's at the back of my mind (perhaps making me see patterns where there are none!).