That wasn't a punctuation error. I omitted a word. However, if you want to nitpick, then yes, I did not end with a period.  Also, I often omit words. That's my curse :(  I did exactly that, in fact, in one of my emails to my professor. After I reread my sent email (because I'm above proofreading), I realized how stupid I sounded as a result. Bah, if I can just learn to reread what I've typed instead of immediately posting, I think I'll at least appear to take more pride in my posts and the like, but I do well enough in conveying my meaning most of the time, IMO.