Hey Spooky,
Yes it is normal for many people following this type of surgery. It can be caused from what archie has said and also the inability to absorb bile salts. There is a medication called Questran (powder) or Welchol (tablet) that is prescribed by GI's to alleviate the problem of bile salt diarrhoea.
My daughter has the problem of chronic diarrhoea and uses psyllium husk to treat hers, as does my son. It has the same effect as Questran/Welchol, absorbs the bile salts and excess water and in doing so bulks up the stool.
If you do down this path be sure and avoid taking medication within an hour before or at least 2 hours after taking the medication or husks.
For some the problem of chronic diarrhoea does take up quite a bit over time but how long is difficult to say. My son had the same amount of small bowel removed as your husband in April last year and although he is still using psyllium and Imodium Advanced at times their use has dropped off since he first started using them post surgery.
Good luck!
Dusty. xxx