"Stroke" is not a very useful term. And the MRI's and the Scans are not necessarily any indication of what has taken place. It os very possible for a blood vessel to "spasm" and restrict blood supply, and also possible for a small clot to develop after sitting for a few hours in an airplane that may momentarily block blocd supply causing the kinds of symptoms you experiences. Try not to worry too much. Keep yourself hydrated, exercise moderately, and I am sure your physician has already run tests ruling out clotting abnormalities. If it happens again kust lie down flat immediately (have someone put a pillow under your feet if they can)and ask someone to summon aide. Stop walking or driving immediately. Many people have such events once or twice and never have them again.
TIA's are mini-strokes that do not always necessarily show up on CAT scan;s or MRIs. They are a sign/symptom of a possible future stroke, but do not worry. See you regular MD, watch your diet, exercise and try to not stress out. Also, do you have high blood pressure? If so, this can result in a future stroke if left untreated.