Sometimes I think we attribute any symptom that crops up to ALS. Or, maybe the symptom has always been there and it's just more noticable because you do not live the life you once lead. You have more time to think about every little thing. I hope that your husband does not have memory loss and it's just a case of over analyzing.
My husband forgets stuff all the time and tells me the same thing over again two or three times over a short period of days. But, this is normal for him, as he has ADHD and is a general air head, but smart as a whip.
If you feel your husband has a serious problem with his memory, you might want to get him tested, just to be sure.
I wish you luck!