The IRS matches up these documents to your tax return.
Talk with your son, and make sure he has reported ,100% of the proceeds on his tax return, and I would ask for a copy of his return for back up (just in case the IRS asks you later why you didn't report it)
Just as long as one of you reports this on your tax return to the IRS, you are okay. The IRS may send you a letter and you will need to let them know what took place.