In short - no - your friend likely did not get a poison ivy (urushiol) induced rash from you. After 4 days, you've likely washed any urushiol that has not bonded to your skin from your arm. Oozing blisters do not spread the oil as the rash, blisters and oozing is just part of the allergic reaction by your body. Now if there is any urushiol oil that may be in or around the home she may have picked it up there. Or she may have gotten into something she is allergic to elsewhere. Urushiol oil which is contained in poison ivy, poison oak, poison sumac and a number of other plants in the Anacardiaceae family of plants causes allergic contact dermatitis (ACD). There are other irritants which can cause allergic contact dermatitis besides urushiol oil. Your friend came in contact with something she's allergic to and it's not likely you.