Yes it could be a symptom but equally, and as with all things ttc, it could just be pmt. I found all sorts of new things started happening once I started ttc - I'm sure some of them had happened previously and I just hadn't noticed but some things were definitely new. For example, I got my first ever blue vein on one of my boobs during one of my very first tww's. How cruel is that! It was definitely a first for me and it's a well known pregnancy symptom so I was sure I'd done it but of course, I hadn't.
Hopefully it is a symptom for you.