I'm pretty cynical about these things - even though I also had a couple of similar experiences after my last cat Jones passed on. They were comforting at the time, and I think that's the key - it's helpful for us to think our animals have not really gone, they're just somewhere else and they're still communicating with us, so if we look for these signs, we'll find them. (These signs are never seen by people who didn't know the animal.)
There's nothing wrong with believing in it if it helps, but I am concerned about "psychics" who take people's money at a time when they're vulnerable and sometimes desperately unhappy.