In your book but blizzard may feel differently. They stated they weren’t going to fix bugs that had minimal effect on the game but that’s pretty subjective.
As for the issue at hand, If you were in stealth and they found you, the pet definitely didn’t respect stealth in vanilla. Vanishing was supposed to completely wipe you off a pet’s attack but I remember something about it rarely ever working that way.
Whether or not this will be in classic is unknown.