Thanks Google! Here are some things I found on Running and Nausea:

Nausea during or after a run can happen for a few different reasons. If you ate less than an hour before your run, that's too close to your workout. It's OK to eat a light snack about 90 minutes before your run. If you eat something that takes longer to digest, like fatty or fried foods, you should give yourself at least two hours. So this accounts for Run #2. But dinner was so good!! Maybe too good so I may have eaten a little too much here...

You might also feel nauseous during or after a run because you're dehydrated. Nausea is an early symptom of dehydration . To avoid dehydration, the general rule of thumb is that you should take in 6 to 8 ounces of fluid every 20 minutes during your runs. During longer workouts (90 mins +), some of your fluid intake should include a sports drink to replace lost sodium and other minerals. And don't forget to rehydrate with water or a sports drink after your run. I Run with a fuel belt which is more or less a glorified fanny-pack with water bottles attached. I have two 8oz water bottles on mine which I downed during today's ~2 hour run. So technically I should have had 36-48 ounces of fluid and I only had 16. That seems like an awful lot of water....what do you drink during your runs?

Another possible cause of nausea during or after running is that you simply ran too hard and overexerted yourself. One way to avoid this problem is to make sure you are warmed-up before starting an intense run and to run at a pace that you're ready for. So this might be it, but I don't think so. While training for the half-marathon last year I did many 10km+ runs and felt fine. I am a lot more prepared and in better shape than during last year's training. Plus I have had other runs under similar conditions this year and felt fine.

Conclusion: I will try to hydrate better before and during next week's long run.