Can anyone explain how a nearly empty early morning bus is over 10 minutes late?

I just moved into Eastlake. I work in Kirkland, and I don't want to pay the 520 tolls everyday, so I need to bus. Thankfully, the bus stops are extremely convenient for going to and from work.I was waiting for the 70 northbound, which is supposed to arrive at the bus stop at 6:07am, but it was over 10 minutes late and I was starting to worry about missing my transfer. I expected maybe 3 or 4 minutes late, but 10 plus seems a bit high. I asked a guy if this was normal for this line, and he gave an exasperated groan and said it is never reliable to be on time. And when it arrived, there were 3 people on it.My question is this: What factors play into an early morning bus being late like this? I can't imagine traffic is a problem, and since it isn't packed, I can't believe that its stopped for long downtown taking on a lot of people at each stop either. The only thing I can think of is the bus is leaving late from its starting point.I just want to know! I did catch my transfer on time and I got to work 5 min early, so this is post is purely out of curiosity.Thanks! via /r/SeattleWA http://ift.tt/2dLhBfj