I'm having similar problems with my pet, but don't have a single piece of T5. I've been noticing it especially in Kara and Gruuls, but it happened in SSC the other day too. My pet goes in, I start my normal shot rotation (BM 1:1) and end up second on threat so I FD, my PET gets aggro from the mob the main tank is on for enough time to go half health and then the tank gets it back. Growl is off, TBW is not on, I didn't use Intimidate, my pet wasn't even showing on the threat meter and he pulled aggro for like 3 seconds, everyone in the raid was like WTF? I ended up having to gimp my damage by waiting 3-4 seconds on almost every pull to keep him from getting us in trouble, but we managed.
I'm just wondering what the deal is because until the last patch came out I wasn't having this problem and it's been happening a lot more often lately and it's really starting to get to me. Someone in the raid even sent me a tell asking me to put in a manual command to make sure growl was turned off, something like /pet_command {growl (Rank 9) off}, but it didn't do anything, wasn't even the right kind of script as I kept getting the "type /help for a list of commands..." after I hit enter.
Any insight would be great.