Okay so now that I think of it, it definitely changes flavor over time. In their product page it says that it is an everchanging liquid. Initially I said how is that possible but believe me it is.
For example, FOOB it is not sweet at all, zero. You can get the tobacco more in the first week. As time progresses, you start to taste cookie or something like that. And then after couple of weeks, it turns into maple syrup.
It is not psychological because I tested this last month. I was out for vacation for a week and through that week when people around me smell the vapor, initially said it smells like cookie and then after a week a group of people said it smells like maple syrup.