Is it normal to not get jealous when you like someone?

In the past when i've liked guys and dated them or got in a relationship with them, i usually would get jealous of other girls being around them or posting on their facebooks. I'd usually keep it to myself though.

With this new guy i like, i'm finding i'm not getting jealous at all and trying not to get so attached so soon. Is that normal?

Why would i go from being jealous a lot of the time to none at all?

I probably shouldn't even question it, but it just seems weird to me.