Congratulations! You made beer. By boiling the decoction, you likely accomplished your goal of getting those pesky melanoidens.
My first decoction, I did a modified the Hoschkerz (sp) route: Mash in at 142, decoct and add back for 159, decoct again for mash out. I missed my 159 rest when I added back in, added some water to get there, and probably didn't hit the mash out temp either. The result was a magnificent BoPils.
In the end, it was fun to try. But I think you can achieve much of it in other, less time consuming ways. That's not to say I might not do it again when I forget that long brew day or others that followed with just doing the mash out like you did.