Well, yes, I have to say that it is normal to have headache after you have taken the surgery. Generally speaking, there are many reasons which can lead to headache such as cold, even the bleeding and injury in your brain. But on the other hand, you should know that eye strain can lead to headache too. And after you have taken eye surgery, your eyes will be sensitive. And in common, if you overuse your eyes, eye pressure will be higher, leading to eye strain. And then it will affect your brain nerve system, leading to pain and headache. For your situation, you are not supposed to take some heavy exercises. Also, do not watch tv and computer for a long time.
Well, so sorry to hear that your retina has been detached, And it is true that after detached retina surgery, there would be some complications right after it at the same time, such as other infections, red eyes, watery eyes, and headaches, this is due to higher eye pressure after the surgery, so you must consult a doctor and take some measures to tackle the problem. Hope you recover asap.
If the headache is just for the temporary after the detached retina surgery, it is normal. It is the not stable eye pressure and eye nerves that cause the headache. Thus, you'd better treat your eyes carefully by not using them too much time with little rest. You should have the good rest for the eyes.