I've been into DIY a little over a year now. I just assume you have been here
DIY E-Liquid
and read this
http://www.e-cigarette-forum.com/forum/diy-e-liquid/127760-diy-warning-please-read.html
and read further here copiously. It is my understanding that some food flavoring may not be too healthy to vape due to contents other than just the flavor and PG or VG, like preservatives, or alchohol. I have only bought one bottle of food flavoring and stopped using it after my first try with it.
When I add up the totals of your recipe 3mlVG, .5ml distilled water, and 1ml of flavoring I get a total of 4.5. What size batch is this? I assume a 5ml? if so you are mixing 5ml your flavoring is at 20%. I also see no amount of Nic in your recipe and assume you are creating 0mg DIY e-liquid. My experience has been that faulty math, not keeping good notes, and not keeping good recipe files were the biggest pitfalls.
If you do not have some kind of free e-liquid recipe calculator, like "E-Juice Me Up" I urge you to look into it. If you are mixing with Nic be careful; after all it is poisonous. I love DIY but exercise tremendous care every time I mix. Enjoy!