Welcome to OTT VC. Nice tractor. There are a lot of M series tractor owners here, but since it wasn't doing it before, it shouldn't be the same problem as the newer smaller tractors are having with jumpy 3pt lifting.
Welcome to OTT Showme from Alabama. The BX25 is a 2013 model. The BX25D is the current version. A lot of people love the BX25/D and they will be able to give you first hand info. By the way, Go Cards.
Welcome to OTT from Alabama. I have the less HP L3200 and it is a great machine so I am sure that you will enjoy the L3800. It will do anything you ask of it.
Sounds like they overfilled it. I would drain enough fluid until it got back to where it is supposed to be. drain it into something clean so that you can use it later.