Dean the dot literally matches everything except a newline. Yes, it does prevent the match from being triggered if proceeded by a space. In fact, if you have done (^| ), you can instead put ( |$) at the end. This will do the exact same thing as your punct and digit.

Phil, would you please freaking calm down? Everybody gets into a quarrel with his or her family, colleagues, and girlfriend and boyfriend once in a while. Besides, we're keeping the post on the right track for a healthy discussion herein.

P.S. Dean please don't flatter yourself. You don't have to follow me back, do you?