I'd ask for a Tensilon test, even though you feel you have no weakness or balance problems. If that clears up your eye, then yup, you got it!
I have generalized MG that deteriorated enough that I was on the sofa playing vegetable most of the summer until I went to my neuro for my annual sleep study. He was the one who noticed the drooping eyelids, and when he showed me how weak I was I was shocked! I ride horses at least 3 days a week until this started, so I'm pretty fit, especially my legs. When this little slight man could push them to the ground, well...... He gave me the Tensilon and 2 minutes later, I won! My balance returned somewhat. Unfortunately, it lasted another 3 minutes and was gone. So was my supposed fibromyalgia pain(during the drug's active period)!