While I can't say much about bullfrogs, I think handling them comes down to the individual frog and whether they are stressed or not. Also make sure your hands are washed in hot water.
So how do you "play" with her? I take my Whites Tree Frog out every night for feeding and sometimes give him some exercise and roaming time out of his 20gal home. I let him walk around on the walls and when he's done, he actually climbs back down onto my hand. Once he launched himself onto my shoulder and startled me as I wasn't expecting it. Sometimes he gets to wander around on the carpet with supervision. My GTFs on the other hand, are only out for feeding and back in, one is fine when you pick him up to transfer him to the feeding area, the other is still panics a little but doesn't run away from my hand like he did when I first started hand feeding.