The flushing is an effect of the buildup of nitric oxide (because the Viagra blocks the enzyme that breaks it down), and it's a common symptom - about 10% of people that take Viagra.

The reflux symptoms are interesting - physiologically I could see how it might have an effect, but it's not a known common side effect.

Keep in mind that the symptoms you mention are class effects, and you might have the same symptoms with tadalafil (Cialis) as well.