I could see that possibly happening if you are pulling out and reinstalling the motor multiple times to weaken it.
I bought a Wera motor puller tool last year. Can't believe I waited so long before buying it. Makes motor removal much easier for me ... and for the pods.
I've been working with the newer NSR pods this week, popping out the stock motors and putting in new handout motors for an event. The plastic is a bit tricky, but that's where my tool has saved me.
But if your experience has been a trend, I'd suggest reaching out to Andrea at NSR to advise - their link is here: https://www.facebook.com/NSRfactory/
They've been very prompt to reply if you PM them on Facebook. Having dialogued with NSR quite a bit over the last year, I know NSR will stand behind their products as they take an immense amount of pride in the quality of their products.