It's actually very common. I got brownish spotting for 4 days when I was 7 weeks. The doctor said it was okay as long as I wasn't cramping and the blood was not bright red. I'm 18 weeks and 1 day now, everything has been great! So don't worry!
I am 8 weeks and 3 days and I had a tiny amount of light brown spotting today too. I called and left a message for my Drs nurse but she hasn't called back. I'm high risk due to 2 miscarriages and having the leep procedure done several years ago. I would call your dr and talk to them to be safe. It may be nothing but it's better to be safe.
Go see your Dr asap. Call and explain what's going on. I had similar experience and was placed on bed rest for 3 weeks. Since then I've been considered high risk for miscarriage. I've made it to 38 weeks. So play it safe and get some peace of mind.