The best person to always ask is the doc, that being said...
I am post CABG X3 1 year. I had bouts exactly like that on the identical meds and it was due to the meds. My doctor wasn't concerned because there were no angina or other chest pains and my BP was good. As time went on and my heart became stronger and more healed, it subsided. BTW, it took a year to feel back to normal and that is a similar thing expressed by many CABG patients.
The Toprol (metoprolol) is probably the culprit.
Dan
I am 12 weeks post cabgx5 surgery. I can only tell you that I have been on the ace inhibitor and beta blocker. They have been winding down my medication as I experienced lots of lightheadedness through this period. I had to go see the Dr. though to have imadjust the medication. Mine got worse from week 3-8 as I recovered. I think it is likely normal but does not hurt to ask the Dr.
Good luck.