Also I've noticed the liquid that I bought with it (same brand) has a slight chemical taste every now and again. Sometimes I taste mango, sometimes I taste chemicals.
I guess a couple questions are in order: Where are you coming from to vaping? Are you currently a smoker?
The reason I'm asking is your sense of taste can get really messed up from smoking. So that might explain some of it.
Another possibility is you are just figuring out your vaping technique. Depending on how you draw the vapor across your tongue, if you pull in air with the vapor as well, and if you exhale out your nose - all of that can influence what you taste in your liquids.
Smokers especially can go through a real roller coaster period when they being vaping. It can start as tasting wonderful. A few days later they notice other things - like off chemical tastes. Then after a week to a month heir ability to taste anything out of any liquid can go completely dead for a while. It does level out after a short while.