My DD is 4 months old and generally a very happy baby, sleeping through the night, feeds well etc... When we're at home she is a very happy, gurgling, smiley baby who rarely cries. However she is a very alert baby and very aware of her surroundings. When we go out she goes very quiet and looks very unsure and more prone to getting upset. I'm sure this is normal and I'm hoping she'll grow out of it, is it just a case of keep taking her out so she gets used to new environments. She is also very weary of strangers and will cry if being held by someone she doesn't know well.