Sounds like you may have a bit of oxidation in your whisky...
There are 2 things you can do to help this a bit - But neither will
completely restore it fully.
1) First thing to do, is to add a dash of cold water to your shot:
This will help "wake up" the whisky, allowing the oxidization to
2) Open the bottle for a few minutes several times over a week's time:
By allowing a moderate amount of air to be exchanged, I have noticed
that slightly oxidized whiskies do much better after going through this
Walter C Hurst