I have not had any chilling experiences, but that just me.
I would consider reviewing the closing exercises to the meditations, as well as following some of the recommendations for the first 30 minutes after a meditation.
It may just be the way you are currently aware of the qi, as you are moving qi and clearing away blockages.
Stay will your practice and call upon your Master's energy for aid.
You are perfection,
Iam2 
