I have had mine running for over 2 months now loaded with prepped tubs. I am expecting eggs anyday.... April 29th (today) is 30 days from post ovy shed from my first girl.

If the vermiculite looks fine I would not hesitate to use it. I looked all 5 of my tubs in the incubator over this week and they all look fine. I used a mix of vermiculite and perlite, but don't see why your vermiculite should not be ok.