250-500cc Oil in coolant

Since I have some broken ribs and can't ride, I decided to tear the bike down and do some much needed maintenance. When I drained the coolant, there appeared to be oil in it. I've dealt with the leaky waterpump seal, but that put coolant in my trans oil. Could it be caused by a leaking head oring?

I wouldn't think so. That would mean it would be premix, and I don't see that as being very likely. With the suck/compress nature of the engine, I'd think it would suck in a noticeable amount of coolant into the combustion which would make it smoke and stink pretty bad.

How much oil are we talking? Any way you can tell if it seems to be gas/premix or crank case oil? Could it be possible that the seal was put in backwards and allowed the oil into the pump? I remember that seal being a bit hard to tell which side was in. I just can't think of anything else that wouldn't cause a lot of other issues.

They are drops of oil, it's not mixed together. If I were to guess maybe a 1/4 cup. I've never had to add coolant since replacing the waterpump seal over a year ago. Since I have the bike apart I might as well take the waterpump apart and inspect everything.