Should I be concerned?

I am almost 16 weeks pregnant (15w5d) and I went to the bathroom and wiped very light brown discharge. I wiped a second time and it was gone. I did have brown spotting at 9w and an ultrasound showed everything was fine. My last appt was at 14w2d and baby was perfectly healthy then too. I'm not in pain at all and I haven't had sex recently. Just wondering if I'm overreacting or if anyone has experienced this?