My Blood Pressure Has Consistently Been Okay For A Long

My blood pressure has consistently been okay for a long time. Generally around 122 over 75 with medication and exercise (swimming). I have stop swimming the past two weeks. I note when I get home from studying at the library (about 5:30 pm) it has been high as 145/97. It goes down around 133/77 after a while relaxing at home and doing some reading. Surprised at my readings like this over the past few days. Also, noted my pulse readings at about 91. It has been generally about 50-60. Some stress, nothing major. What is going on? Should I been Concern? Will be getting back to swimming again. Thanks.