My cycles range anywhere from 24-30 days, so in my opinion, yes, you can be late with out obvious reason. I assume you have not been sexually active, since you did not mention that in your question. Just to break it down, most woman ovulate between day 11 and day 14 of their cycle. The first day of menses is the first day of your cycle. The second half of your cycle, between ovulation and the beginning of your next period is called the Luteal Phase. The Luteal Phase is 14 days, and it is not effected by stress or anything else (lots of old wives' tales out there). If your body ovulated late, then your period may be considered late by you, but according to your body, it's right on time. If you skip a period, and you have not had intercourse, then chances are your body did not ovulate. Skipping ovulation occasionally can be normal for some; however, it can signal there is a non-serious hormonal disorder. If your cycle is normally 28 days, and your last period was Sept 2nd, then you should start on Sept 30th. If you do not start by the end of next week, then you should talk to your Mom (assuming your young) or follow up with a Dr. It's probably nothing though if you have not been sexual active.
Mom of two babies :)