Low blood pressure?

At my last appointment the doctor mentioned my blood pressure has been low (96/56). He said he wasn’t necessarily worried about it, just something he was going to be keeping an eye on.

I’ve never had low blood pressure (in fact, I usually experience the opposite). What could be causing instances of low blood pressure? My appointments are generally later in the day... I’ve had several meals before it’s taken so it’s not food related. It’s just so baffling to me! 🤷🏻‍♀️