Anthony Rucki's Date of Birth

My great Grandfather Anthony Rucki committed suicide in 1929 by hanging himself. I was able to obtain a copy of the death certificate in which the informant was his wife, my great grandmother Adela (Kielb) Rucki. She gave his date of birth as 1 Nov 1890. For many years I've stuck to that date not having any other documents to prove otherwise and also fairly confident his wife would know his date of birth. As I was doing a search on Ancestry.com today I was trying to find Anthony's WWI Draft Registration Card. An intial search didn't turn up anything. I then did a search for RUCKY which has never been fruitful in other search engines but I've been having some good success in my other lines lately by really stretching the spelling variations. The spelling variation worked! I found Anthony in the first attempt! Or atleast I thought it was my Anthony. He lived at 2821 Buckeye in Toledo, Ohio which is the address on have on him in other documents. But the date of birth was wrong. Grandma Rucki reported on the death certificate his date of birth as 1 Nov 1890 and place of birth as Poland. The draft registration card filled out by Anthony himself reports his date of birth as 1 Nov 1888 and place of birth as Somza, Russia. For social reasons or maybe she just reported it wrong Anthony's year and place of birth I have now changed in my database to the date and place that Anthony reported himself.

I've sat and wondered why Adela might have got it wrong which I might never discover. He was 7 years her senior with a birth year of 1890 and 9 years her senior with a birth year of 1888. Could this be the reason? I've also considered that the stress of discovering her husband's suicide could have had an impact in her state of being when she gave the information for the death certificate.