It depends on where the cables were attached to her car
If the cables were attached to the battery, then it's theoretically possible that you could have damaged the battery — but the odds of that happening with the conditions you state are vanishingly small. The flow of electricity isn't dissimilar to the flow of water — the shortest path is the path the electricity will take. It'll be drawn from the battery before the alternator (it's not quite that simple, but suitable for this explanation as the results won't change). But you'd need to keep those cables connected for a lot longer than a quick spark for damage to occur unless the battery was ready to die anyway. Automotive batteries are necessarily robust and very hard to damage in this way.
Had the cables been connected to the alternator (never a good idea!) then there's a higher chance of a problem because the coils in the alternator can overheat much faster than the battery can. I could be wrong, but I've never personally seen a car that made the alternator that accessible. People either use the battery posts or jumper posts provided by the manufacturer, which are tied to the battery.
In any case, had damage occured her battery or engine light would have come on and she likely wouldn't have driven very far.
No, you're cool. I can't count the number of times I've mistakenly shorted jumper cables. Frankly, if you held them together long enough to seriously raise the odds of causing damage, you'd likely arc weld the cable clamps together — a car battery has that much power.