The Northern Irishman made a young fan's day at last week's British Masters by handing over his golf ball.
Speaking of the gift, McIlroy admitted that Keane's snub while on international duty with the Republic of Ireland left the four-time Major winner determined not to leave his fans disappointed.
"I went and asked him for his autograph at the Portmarnock Links Hotel [in Dublin] and he said 'no'. I'm sure he's alright, but it sort of stuck with me ever since," McIlroy told BBC Sport before the Alfred Dunhill Links Championship in Fife.
"I've had it go the other way, where I've asked someone for an autograph as a kid and they didn't give it to me and I've never liked them since. So if a kid asks me for an autograph, I always try to do it.
"Every time I need a new [golf ball] I look for a young kid in the crowd between holes to give it to them. I was surprised how that little moment last week became so big. But it just shows what such a small thing to me can mean to a kid, and that kid might be inspired to go and play."
The 28-year-old heads into the Alfred Dunhill Links Championship on the back of finishing second - his best performance since January – behind Paul Dunne in the British Masters.