If you switched to herbal tea you really don't need to worry about stains anymore, but if your tea is fruit-based and you drink a lot of it it may cause a problem. Heavy exposure to some herbal teas can erode tooth enamel. There was a number of researches conducted to prove this fact and here is what one states. The scientists soaked extracted teeth for an hour in various herbal teas, black tea, lemon-flavored instant iced tea. The most damaging to enamel were the iced tea and the herbals that have a significant level of fruit acids. The only kind that neither caused erosion nor stains was chamomile.
So from now on if you still want to enjoy tea and drink coffee try to alternate them during the day. Once you have a cup of coffee rinse your mouth with warm water to wash off the patch on your teeth that stains them.
Hope my tips will be useful for you and your teeth :)