That's weird, yes! I ran 30km on Sunday 5th September, and was pretty tired after it. About 3 o'clock on Monday morning, I woke with pains in both feet, stretching up both my shins. It felt like cramp, but was on the front of my legs, not the muscle areas. No amount of stretching alleviated the pain. It dissipated after about ten minutes, and I've not had it since.
I rested for two days, and since then I've run 5k, 8k, a 20k on Sunday just gone, and 10k today. I've cycled 10k and played football once and there has been no sign of the pain again. I've had shin splints before, and it definitely wasn't that.