Questions were raised over the Brit's fitness after he just edged into the final by finishing in third place.
"Dave is in a really good position, I wouldn't take too much from his qualifying round as he had to sit and wait with anti-doping following his 5,000m win," BBC Sport quotes Grey-Thompson as saying.
"He also didn't want to show his hand too soon. He was toying with them slightly, he will be in much better shape tonight."
Weir won his first gold of the Games in the men's T54 5,000m final.