I think the previous estimates might be a bit high. There is a significant difference between 3.75 lbs honey in a gallon batch and 3.75 lbs honey added to a gallon of water because of the increased volume.
The recipe is written 3.75 lbs honey and 1 gallon water. There are approx 12 lbs honey in a gallon. So, 3.75 lbs is approx 0.3 gallons (3.75/12=0.3). That gives a batch size of 1.3 gallons (water+honey).
The sugar content of honey can vary, but 36 points per lb is a good average. In 3.75 lbs of honey, there are 135 points of gravity (3.75x36=135). In a one gallon batch you'd have 135 points or an SG of 1.135, which is what Illuveatar calculated. This is 1.3 gallon batch, so the gravity is diluted a bit. You have to divide by the batch size. 135 points divided by 1.3 gallons works out to approx 104 points per gallon (135/1.3=103.8), which translates to a specific gravity of 1.104.
I hope that makes sense.