I think, since TIAs and migraine auras can have similar effects, it is a good idea to have this sort of thing checked out the first time it happens to you. However, I think there are differences between the two: with a TIA, the onset is normally very sudden, whereas with migraine aura, it steadily progresses before gradually getting better (eg starts like a little blind spot which gets gradually bigger, becomes funny flashing lights in the corner of the vision or little clear, sparkly shapes, etc). Also, I think TIAs are more like the vision loss part of a migraine aura (losing all or part of your visual field temporarily) - I don't think you would normally expect the other visual effects. Neither TIAs nor migraine auras cause permanent damage, but a TIA is often a pre-cursor to a proper stroke, so must always be taken extremely seriously and if there is a chance that you had one of these, you should always check with a doctor. I don't think it is uncommon for people who get classic migraines to start getting more of the visual effects as they get older, though (but then, of course, as you get older, you are also at a higher risk for strokes).
I know that migraines, strokes and TIAs can have remarkably similar effects, given that it is even possible, with a very severe migraine, to lose control of, eg an arm on one side of the body, temporarily, or to have temporarily slurred speech. I've only ever had migraine auras - never had the headaches. I find them quite an interesting experience.