Yes, you are very correct to be greatly concerned.
You can go to the American Heart Association's site and search for stroke risk factors. The time when you're most likely to have a stroke is when you've already had one, or had mini-strokes. Having high blood pressure also makes you at risk. Having had a heart attack means you're at extra risk.
Many years ago, physicians believed that it was okay to have a blood pressure which was equal to 100 plus your age. It's now recognized how wacky that is.
Having a difference in BP between arms might also indicate an internal problem.
are you on any blood pressure meds? can you get a 2nd opinion?? what about getting an appt with your cardio doc....i'd be concerned as well.