Hi, and welcome to Basenotes!
You know - it's a hard question to answer. Yes - our sense of smell can change from day to day and even hour to hour, so just because it smells different, doesn't mean that the sandalwood isn't there. Sandalwood is a subtle scent, and your sense of it can change easily. I know this because I have had scents where I said "Where is the sandalwood?", and then I came back to them, and it knocked me over. So there is that.
There is also the possibility that the layered base had some combination that really clicked for you. This is entirely possible. I would tend to think that sandalwood would be more apparent in a SINGLE fragrance, but things don't always work out the way we thing they should.
Welcome to the reality of fragrance. It's very, very time-dependent. This is why you should never get involved in an Aventus batch variation thread - not everybody there is actually smelling real differences. The only way to rule out temporal differences is mental training (doesn't always work) or side-by-side comparison.