This happened years ago and while I was at work so I know that they did the expedient thing so they wouldn't have to wait for me. I thought about this the other day because this son is not in the best of health and if something happens to him will I have so that whoever he might have left his estate will have a free and clear deed.
If you were not a resident in that home, it was not necessary for you to sign the deed for a home solely in your husband's name. If you were a resident, you had homestead rights that were not transferred to his son. It might create a title issue, (if you were a resident). It would be the Title Company's obligation to sort this out at the time of a transfer out of his name.
This answer does not constitute legal advice and does not and is not intended to create an attorney-client relationship. The law may vary depending on the state in which you reside. It is intended only to give some direction in which to seek assistance.
General Practice Lawyer
If this was a home in which you lived, you probably acquired homestead rights in the property which were not conveyed with the quit claim deed. If you did never lived there, your signature was not necessary.
Concerning transfer upon the son's death, unless he already has received good legal advice, I suggest he see an attorney soon to consider the interest in the property and general estate planning.