The harbor seals here in SoCal (at least in my experience) tend to be more wary and less playful than elsewhere. However what you describe sounds like play behavior, and I've experienced it both here and elsewhere... usually with the younger harbor seals. The same thing goes for California sea lions... I rarely have true interactions with them here in our waters, just swim bys. However elsewhere, like at Los Islotes in the Gulf of California, they are almost a nuisance with their playful nips on fins, wetsuits and BCDs. They also steal snorkels, which was a reason I stopped diving with one.