I think your husband is right to be concerned. We always wanna look and make sure that its not pain, but I personally think that is unacceptable behavior no matter what the reason is. Major has never tried to lay down on me while riding...but he has tried it on the lead line. When he started it...I asked him to walk in a different direction. He then looked up at me like he was suprised I was there (I know it sounds strange...but I swear he looked suprised to see me). I think horses forget that we are there sometimes. When your horse starts acting like hes gonna lay down, point him in a different direction...that will get him thinking again.