I melted a piston a few months ago, initially it just looked like a set of pistons and a rebore. Erm ....NO, turned out head had taken a few knocks which couldnt be machined out and the block had a big hole in it too! By the time everything was completed ( done right )i was looking at around the 5k mark!

As mentioned if its fine just now then just chip it and see how long she lasts then you could worry about rebuilding later.