Just a thought, but it sounds more like moisture got between the battery post and clamp. When it does, lead oxide forms, which is a VERY poor conductor of electricity. When you turn the key to start, it will actually arc through that mush but it won't always get enough connection to start. A couple tries and the post will heat up (warm enough to feel if you touch the posts) and temporarily dry a patch for it to start through till next time it gets wet. The rsistance can get so bad that it can melt the battery post off, but usually the alternator gets burned out from the open circuit first.