I would like to step in and confirm that we have not changed the RNG that affects pet rescues. If that wasn’t clear from my last comment, I apologise, so have restated it.
I told the team about your circumstance, but it is inevitable that within RNG based games that streaks will occur. They are very rare, yes, but when it comes to probability everything is possible.
In regards to faction pets, they were never meant to trigger in random pet rescues. That they did very briefly after 4.1 went live was a bug that we fixed. This is what the patch notes have to say about faction pets from 4.0, and is how they are meant to work.
The new pets that were introduced with 4.0 that can be gained through Pet Gnomes are as follows.
I hope this has helped clear things up. 
