Whither my girl?

My chatterbox seems to have gone into hiding. From when she was only a few weeks old, you could hold her head in your hands and coo back and forth with her for ages (ages = 15-20 min in baby-time). Early last week she began to increase the volume of her hiyas, gurgles, tongue-rolls, and ha-uuiuuhhhs, but she's gone strangely quiet of late.

It's hard not to ask myself if I did something wrong. Did I make her more passive by wearing her in the sling too much? Am I not playing enough or engaged enough with her? Am I letting her sleep too long because it's convenient for me? Did we shush her too much? ... I suspect these to be foolish questions driven by my perfectionism, not by her good.

Or is she just becoming more interested in observing the world and therefore splitting her time between quiet observation & playing with lips, palate, and tongue?

I don't know her well enough to say. She is my enigma as well as her own. We stare at each other: I, wondering who I'm seeing; she, wondering at her seeing, but perhaps not yet at me.