She just might be, especially if she's off feed and refusing the male for a month now. My first (and only) clutch was subtle as well, I missed ovy and then my snake didn't swell up like I thought she was supposed to, and then she had a slight ridgeback. So when I went off and started freaking out on here, asking questions, all of a sudden I had eggs.
When is the last time she shed for you?