dude, that is not his lines.
"Bardock says HE remembers everything."(fasha)
"He MAY remember every second of every battle, but he remembers nothing of his personal life..."(tora) "Allow me to demonstrate. Bardock, do you remember what day yoru son was born?"
"I don't know...but, that was a long time ago..."(bardock)
"No it was not you lazy bum. Yesterday?"(fasha)
And as Goshi said, people DO change over time, which he did!!
Not to mention, as Tora said, Bardock doesn't remember ANYTHING about his at-home life. So yeah...plus, he was on a mission just a few hours before!! How could anyone expect him to know?
btw, the link to the fic in my siggy is how Bardock would've treated his sons, had he beaten Frieza. You should all read it. But I was a starting writer through the first few chapters, so excuse errors for the first about 10 or 15 chapters, ok?