I was but don’t feel that was an issue, they didn’t require proof of purchase if I remember correctly but I also registered it right away as I do all optics. You can always call them and ask.
Get the serial number from the seller before you buy, if the seller will not provide don’t buy. Also contact Doug at cameralandny as he has had the Hd-b 2200 for less then $1500 and the hd-r for around $1000, they are demos but it’s a trusted seller and good deal on barely touched optics.
I do wonder how it works if the original buyer never register them as the electronics warranty is for a limited time but some have had new replacements given even after this period is up.