I thought I was the only one.
I used to make alot of Chai, thinking I was gonna drink it the rest of the day, well anyway, when I left it over night , in the morning it would be the grossest thing ever! So I experimented and left it there 2 more nights, the longer I left it, the thicker it got...........
I then starting placing my leftover tea in a glass jar with a lid th next time, and nothing happened.
So just make sure the jar is nice and clean, and put the tea in there while its still hot =o)