I'm baffled by the vagaries of my palate. I'm generally a red wine drinker, and I'd guess my red-to-white consumption ratio is about 4:1. But the last couple of times I've consumed red wine, I've been put off instantly. It just strikes me as oddly heavy (as if my taste buds were saying to me, "not more fruit, oak, and tannins, ugh"). I don't think it's the particular red wines I've been drinking either--they've been wines that I normally enjoy. Guess it's time to switch it up to white wines for a while and hope this mood passes.
Taste is a chemical reaction. You're body is always changing, ph varies... and there's what you've eaten lately and the rest. I'm sure we've all had stretches where nothing tasted "right" only to return to "normal" at some point.
In short, your palate is constantly evolving.