Honestly, yes. It's because your chickens will panic and stick their heads through the chicken wire eliminating the 1.5 inch gap. If you make a gap inside the run, it needs to be more than the length of a full grown chicken neck plus the longest reach of a raccoon. It's probably not...
If you have raccoons, use 2 feet of hardware cloth around the bottom of the entire run including the door. If you use chicken wire, not only will they be dumb enough to stand by the fence, they will stick their heads out and make it easier to have them bitten off!