Situationally, it could be angry, but there are other reasons to end your sentences with a period. I think the real problem is that the short-text medium makes

Situationally, it could be angry, but there are other reasons to end your sentences with a period. I think the real problem is that the short-text medium makes it hard to accurately convey emotion in the same way that tone and body language do, and so things like periods, emoticons, interjections, exclamation points, and phrasing have to carry that load.