Leaving out first person personal pronouns

I’m finding that more and more I’m leaving out personal pronouns in emails, blogs and social media.

Especially at the beginning of messages.

So rather than, “I’m drinking French Roast coffee today” I write, “Drinking French Roast coffee today.”

Or yesterday in an email, “Working on a website and thought about this…”

I’m sure it’s related to social media status updates but I wonder why. What brought about the change in my/our language?