That isn't a penalty but your site got tanked.
Google hardly penalize a site, if you lose your ranking and still indexed then it's not a penalty.
hey man , not much changed , i already did that before postingI would suggest evaluating your link profile and see if you notice anything strange. Since you haven't built any recently it shouldn't take too long to determine if something fishy is going on. Also as someone mentioned previously creating more quality backlinks would be a great idea!