I know for me when I was on BuSpar my heart rate declined and so did my blood pressure and has stayed on the low end of the spectrum since getting off of it last year. Call your doctor just to be safe and good luck!
Buspar does have a tendancy to lower heart rate due to higher raised rate with panic and anxiety. Are you having any symptoms with the heart rate drop such as light head, beating hard or fluttering feeling? Also, how do you know your heart rate is lower?
No, in my opinion you should not be concerned. Buspar can help with anxiety so if your anxiety is much lower your heart rate can also be lower. Your are still very much within the normal range of heart rate. Of course I'm not a Dr and if you're still concerned give your Dr a call to see if this is normal.