Mail her your Playbill with a SASE or hit the stagedoor after the show another night. I would assume most actors when arriving for the show are just looking to get inside and prepare.
Also, I've seen bigger names, like Janney, being dropped off by their car before a show wearing sunglasses and b-lining for the door, avoiding eye contact. You would need to literally shout to them or cut them off to get their attention and that is rude. To disregard social cues such as sunglasses or avoiding eye contact is creepy and stalkerish.
"The sexual energy between the mother and son really concerns me!"-random woman behind me at Next to Normal
"I want to meet him after and bang him!"-random woman who exposed her breasts at Rock of Ages, referring to James Carpinello