Good luck. You can never be too careful or too vigilant.
A very quick search of the literature turns up a decent amount of research on headaches after cerebral angiogram (where it is more common in women than men), but not much after coronary angiogram. The cerebral angiogram literature does mention reaction to contrast dye as a cause of some of the headaches observed, so I certainly wouldn't close the book on that possibility.
Stress test followed by invasive diagnostic angiography is the traditional path that possible coronary blockages are ruled in or out, but less invasive approaches may be better for some patients, especially older ones. Several trials from the past 7-ish years have shown that noninvasive testing such as with CT scans seems to do just as good or better than invasive testing -- but I don't know if Medicare and the private insurance companies have caught up yet as far as reimbursement goes; I think it still varies by region/plan. In the future, if invasive testing is ever proposed, ask why they are suggesting that instead of noninvasive testing. The most notable clinical trials in this area are SCOT-HEART and PROMISE.
As you may remember, I cover cardiology, so don't hesitate to shoot me a PM if you ever have any questions about anything heart-related.