I don't understand how microwaving water can change tea. Not necessarily doubting, just not understanding. After all, there's a famous story about a Lady So-and-So who proved scientifically that she could tell the difference between tea poured into milk and milk poured into tea. Apparently, y'all serious tea drinkers (as opposed to us casual tasters) are a bunch with mysterious powers.
However, if you do decide to heat your water in the microwave, don't do so in your mug, which is probably not microwave safe. The glaze will eventually crackle, water will seep in, the mug will develop hot spots when microwaved (very hot spots), and the mug (and possible a little of your skin) will be destroyed. Instead, heat the water in a microwave-safe container, like plastic or pyrex.
Also, while unlikely, it is possible that water can be superheated in microwaves without turntables and "explode" when disturbed, so be careful.