No, you are not imagining this.

This is a photo of Maya and Hana playing together (with a fast-moving plastic slinky). They are kind of into playing together these days, actually. Maya likes to tickle Hana and pat her on the head, like a dog. Hana likes to chase Maya around and play with/try to eat whatever Maya is playing with, and Maya shares maybe half the time, even without being asked by a parental figure.