I was still very involved with my chapter after becoming an alumna, but I remember the first rush as an alum. Sure, I helped out as much as I could by doing the background work -- slaving in the kitchen, really -- but it didn't really hit me until my first Pref as an alum. I could hear the songs they were singing and hear their voices, and it made me miss being a collegian.
I kinda see this as a good thing though. You may be 1000 miles away from your chapter, but when you do get to see them, your newest sisters will be able to see that the bonds of sisterhood don't end with graduation.