There could be another reason for the low pH. I've had a similar response from an English brewer using Crisp Amber malt. The maltster calls it a 'roast' malt. But, when the brewer planned the brew with Bru'n Water, he assumed it was a crystal malt. He measured pH and found the mash was a couple tenths low. When he went back and entered the amber malt as a 'roast' malt, the pH prediction was almost perfect.
I guess its possible that this Red malt may have a similar response. Try it as a roast malt and see if the prediction is closer to your observation.