Don't people talk differently depending on the company they are in? I think most people will have different levels of trust in their acquaintances, at the extreme what I might say to my significant other will be different to what I talk about with a work colleague.
The problem with social media is that it is typically a megaphone to everyone.
Absolutely, and it is completely normal. The Japanese even have this concept explicitly ingrained in their language - 'Tatemae' (socially acceptable reality) and 'Honne' (informal, personal reality) [1]. This is essentially the difference between saying "I'm fine" or "Actually, my dog just died" to a random person or to your close friend.
But is it really so much that you're broadcasting, or are others eavesdropping. While it would be weird to say that to a stranger, in facebook your ostensibly informing your friends. That might make difference.
The problem with social media is that it is typically a megaphone to everyone.