>>1038240Penny usually has a plan, or is prepared for the outcome of her actions. But with Aggie, she went out on a limb and completely out of her comfort zone. She didn't really know how Aggie would respond. And Aggie could have pulled a, "Stop messing around." and not taken her seriously, or worse, she could have been offended. Considering the Lisa incident (where Daphne and Sara were making out behind them and Lisa got close like she was asking to kiss Aggie).
So, she's making herself vulnerable, and Aggie realizes this.