That is a bit odd... but what I would assume is that the OBC, radio, etc are very briefly 'waking up' when they first get power (when you attach your meter) then they quickly go into their sleep (low power) state. If it stays at 0.03 as long as you keep your meter connected, I would say you are good to go.
I tried to nurse the battery along in my beater last year. It wasn't worth it. (Speaking as one of the cheapest people I know) I replaced it and forgot all the trouble I had trying to eke out the last bit of life from a dying battery. I'd say replace it and see if you have the draining problem with the new one.