Hi Danielle,
I would definately keep an eye on it. I had similiar type pain, with lower back ache on and off for a couple of days prior to going into early labour at 32 weeks. Luckily, we managed to stop labour with some meds and bed rest.

So I'm definately not saying that you will go into early labour (hope not), but I'd just keep and eye on it, if the pain doesn't go away (like it had yesterday), get worse and speed up I'd definately call the hospital, just incase, it's better to have a false alarm than an early labour

Oh and another thing, alot of women get this sort of pain when their bodies start to prepare themselves for labour, so as long as it doesn't progress into anything further, it's a good sign that your body is doing what it is surpose too.

Good luck.