I can sure vouch for differences in ages on census records. I have just been working on a collateral ancestor who was counted on the 1860 census in Pontotoc County twice. The counts, by the same man, were 10 days apart. On one she is listed as 46 years old, and on the other as 51 (she was likely 53). Most of her children were the same, except for one who aged a year, and another who lost a year!