The odds of getting anything from only the tip of your penis being inside a vagina - if that even happened at all - are astronomical. HIV transmission is rare even in events that involve full penetration and intercourse, with extended rubbing of the penis inside the vagina.
I wouldn't be very concerned about this at all, though I'd probably not visit that venue again.
Even if you had complete unprotected vaginal intercourse the risk is not high , mostly she is not hiv +ve and also the possibility she allowed you penetrate her vagina is very low cause she cares to protect her self more than protecting you... so when you collect all those items together the result that you have very low risk close to zero .As curfewX mentioned astronomical risk .
Pep is indicated for high risk exposure with hiv positive partner but to take it or not is your personal decision.