I've done it more than once. Usually a week at the most but to be totally honest, I dumped it, hosed it out and brewed. No problems at all. In fact, I've won gold medals with a kolsch that was brewed right after this. I really don't believe that there are any perceptible aromas/flavours that come through in the final beer given the boiling etc that happens after.
I try not to leave grain in it but when it happens, I really don't worry at all. So, I'm not surprised your wash routine worked. Once when it was really bad, it got a shot of bleach and water and I worried more about the bleach than I do about the grain. Not suggesting you do this but it's not the end of the world by a long ways.