if you remove easter peeps from their package and place them on lollipop sticks, will they last 4 weeks in a ziploc bag?

Are you individually packaging them, with the plastic around the peep and the stick poking out of the bottom of the bag, with a ribbon tied? If so, air can still get in around the stick area, so you may want to put them all into a larger zip bag, removing as much air as possible (don't use a vacuum sealer though.) peeps tend to harden up pretty quickly when exposed to air.