Hi Bill,
Your bimac has decided that you don't represent a threat, that you often provide food, and that you are otherwise an unknown that needs to be investigated. BTW: Did you know that octos 'taste' with their suckers?
It's very common in public aquariums for GPO's to not only learn to recognize their keepers, but to develop a hierarchy of most favorite to least favorite. IOW: The same octo will enthusiastically(?) greet one keeper and immediately hide from another. I saw a case once where a GPO pushed food away because it had been given by a human he didn't like.
Assuming that bimacs are not a biting threat and that you are careful to have clean hands (and arms!) when reaching into the tank, I only see one potential downside. Octos don't have any concept of a ringing phone or of any of the other artificial emergencies that would cause a human (you) to need to quickly disengage. As you've probably seen already, octos don't always do things quickly and there is the potential for injury if you needed to get the octo off of you in a hurry.
Tactilely yours,
TPG