My BP went up to 160 (which was always normal) for one day. Should I be worried?

No. If its usually normal and there was a good reason (intense activity, pain, etc (then this is not alarming. I'd repeat the blood pressure regularly, though, at different times of day and in different environments to make sure it's not high.
Be mildly concerned. At minimum, you need to give some thought as to why it was elevated at that moment and to follow up with your physician to have your blood pressure rechecked, at least once. Common causes of one time or infrequently elevated blood pressure are anxiety, stress, exercise, use of decongestant pills and nasal sprays, and drinking caffeinated beverages. An ekg, blood tests and urinalysis to be safe.