mare/gelding behavior

Question
I have 3yr old welsch/quarter gelding, I got him may 27,2007, gelded him that day, started riding him 3 weeks later.  He has been super, my 6 yr old niece even rides him, I have just 2 wks ago moved him to my friends house where there is a very lonesome 15 yr old mare who was very happy to see another horse, she wouldn't even let him walk away from her the first day, (he ignored her,she would back her rear to his face & pee alot, I'm guessing she's in heat, now he has been nipping her rear end not leaving any marks or any thing and has even tried to mount her once.  I s this just because she was in?  He was with other horses before here and there was not problems except the one gelding was mean to him,

Answer
Hi,
Many geldings enjoy mounting mares. In some cases it is a dominance issue, in others the gelding still thinks like a stallion and in a few, the horse was not gelded correctly. The one thing you do need to be careful of is infection, if the gelding penetrates the mare.

Lisa