Theoretically yes, but it shouldnt be anything you need to worry about. If you make a starter wort from DME and water, the mash chemistry was somebody else's concern, and the wort will will be well within the acceptable range for fermentation. Some minerals in the water will help, of course, but if you add a little nutrient you should have the essentials covered. Short story long, I've never checked the pH of the starter wort, and have never heard of anybody else doing so.