I Had A Mild Heart Attack 4 Weeks Ago, And

I had a mild heart attack 4 weeks ago, and tonight my blood pressure machine says I have an irregular heartbeat. My pulse is about 20 points higher than normal. The last reading I did was 111/80 with a pulse of 86. Is this something I should be concerned about. I have a very mild pain in my chest, but I'm thinking it's because I played golf today for the first time in awhile.