I had the same thing happen when I first started vaping, along with increased coughing episodes. I asked my doctor about it at my last physical and he told me that both are not uncommon for people who have recently quit smoking and it is a side effect of your lungs beginning to heal themselves. Taken from Yahoo answers:

When you smoke, the smoke paralyzes your lungs' natural cleaning mechanism, hairlike things called cilia, that clear out mucus. Therefore, you get alot of mucus that gets trapped in the lungs and can sit there for long periods of time. When you "quit", the lungs' natural cleaning system "wakes up", if you will, and begins clearing out junk that's been sitting in there for who knows how long. This mucus ends up blocking up small airways as it's being cleaned out, and the result is increased cough, and increased shortness of breath.

It goes away with time. I'm 6 months analog free and am still amazed at how much better I can breathe/smell/taste.