Help! Extensions falling out like crazy!

I just had my first tightening about 3 weeks ago and so far I've lost about 6 extensions. I'm not sure why. The first 2 1/2 months after having them first put in I never lost one, and now-6 in 3 weeks! I went to the same gal using the same method (pinch praid at Hair Police). I wash my hair once a week and use the same styling method (blow dry then flat iron). The only change I've made was switching from my old shampoo (Rusk "Pure") to a new one called Sala--a Japanese shampoo carried by Hair Police that is incredibly silky. Could using this once a week be making the extensions fall out? I also use Goldwell Kerasilk conditioner from just under the braid down.

Tammy