Fainting?

Caitlin
I'm four weeks postpartum and had a fainting spell this morning (thankfully not while holding my son!) just after starting my breakfast. I've been eating regularly, I'm not dehydrated, and haven't been taking any new meds. My MIL decided to take my BP, which read 103/64. Could that be why I fainted? Has anyone else experienced this? Any other reason why this might have happened?