Did you remember to update the registration during the transaction? Unlike 121.5 MHz ELT, 406 ELTs are registered with NOAA and this registration needs to be updated when the aircraft is transferred.
The website to update this information can be found here.
Here's the information from NOAA's FAQ:
You'll also want to remember this is not a “one and done” operation. You'll need to renew the registration every 2 years. You'll also receive a new decal every time you renew with the new expiration date.
Making sure this information is up to date and actually lists the correct owner/emergency contacts makes sure that Search and Rescue can do their jobs more effectively, especially in the case of a real emergency and not just an inadvertent activation.
I have a 406 MHz ELT as well as a portable PLB in my flight bag. Both are registered with NOAA and I've had two renewals. They emailed me since my registration included my email and I've kept it up to date. Keeping your contact information up to date on their website is important.