Ajayi reportedly wasn't happy after being named the backup to veteran Arian Foster, but Gase said everything is good now.
"He's back in meetings, he's back in the building," Gase said. "We left him back. That was my decision and we've cleaned that up. We'll move past that and basically this is a new day for him today."
Miami hopes Ajayi, who had an unspectacular training camp and preseason, can provide a physical presence to a running game that gained just 64 yards on 20 carries last week.
If Ajayi can't get the job done, Miami might turn to Damien Williams, rookie Kenyan Drake or Isaiah Pead, who was inactive last week after coming off a hamstring injury.
Gase also said he needs to trust quarterback Ryan Tannehill a bit more. Gase, who calls plays, said he should have been more aggressive from the start of the game.
"I was mad at myself because I felt like I should have gone, to what we ended up going to (on that drive), earlier in the game," he said. "But I kept talking myself out of it.
"And he kept pressing me to get to that, basically what set up that drive was some of those plays, he kept pressing me to get to that stuff and I kept talking myself out it and then finally, once I listened to him, then we marched the ball down the field.
"I mean, it was a great lesson for me as far as, when he says to go to something, we're going to go to it."