Puratek RO/DI Cartridge Question

[Madreefer]

So I have a Vertex Puratek RO/DI unit. I had problems with it in the past which are now fixed. I did a water change on the weekend and now the built in TDS meter is showing 01PP. I chaged all the cartridges and the membrane in the beginning of Jan. I think this is a little early to be reading that. Yes/No? I really dont want to be buying a new membrane this soon. Would just changing the sediment filter be enough? The unit is filtering approximetely 50-60G a week. I could be just worrying too soon. I hope so, quit my job and now a poor student until mid Jan.