Happened to me too. I scoured the web for any information I could find. Here's a summary of what I found, excerpted from a write-up I did on ecigs:
Vaper's Tongue- Sounds scary doesn't it? Well, it isn't. What it is is weird. Really weird. It's something that can happen to new vapers after about a week or two. It doesn't happen to everyone, but it did happen to me. Vaper's Tongue is a phenomenon in which you stop tasting your vapor. You don't stop tasting anything else, just your vape. Chocolate, soda, meat, fruit, vegetables, bread, and anything else you can name tastes just fine. See, I told you it was weird.
No one in the vaping community knows why it happens. Theories are abundant and contrary: It's the PG. It's the VG. It's dehydration. It's taste buds waking up after a long tobacco induced coma. Any of which would make sense if it was a complete loss of taste, but it's not. Only vapor. Weird, weird, weird.
By most accounts it happens about 2 weeks after beginning to vape, and generally lasts 1 to 2 weeks. It happened to me 17 days after starting, and lasted 9 days. So, apparently the reports are accurate on that account. Recommendations on what to do about it range from common sense to lunacy. I'll save you the trouble of sorting out the good from the trash, and tell you the recommendations I tired:
Drink extra fluid, and keep it in your mouth longer. Use it to rinse your mouth before swallowing.
Brush your tongue along with your teeth.
Switch e-juice flavors if you have more than one.
Use a dry mouth mouthwash. Biotene is your friend.
I did all of those. Did it work? I don't know. I do know the Vaper's Tongue went away. Maybe it would have went away by itself anyway, who knows? In any case none of those things hurt to try. I still keep some Biotene handy in the event I start noticing any dry mouth. It's also a good pallet cleaner when comparing several flavors at one time, just FYI.
One good thing is that if you have some juice you don't like, it's a good time to use it up.
The bottom line is that Vaper's Tongue is annoying, but temporary. If you're lucky it won't even happen to you.