"We did have one incident in India two years ago. Nothing happened other than that one phone call," said Rajah, who refused to name the player other than saying he was not part of the World Cup squad here in the Caribbean.
South Africa drew a five-match series 2-2 with one match rained off in late 2005.
Johan Botha, Albie Morkel and Justin Ontong were the three players who were on that tour, but are not part of the current squad.
"We passed the information to the International Cricket Council (ICC) Anti-Corruption Unit (ACU) and they assured us that they would handle it," said Rajah.
The official said the players were more aware and cautious now.
"The players are trained to phone as soon as they've been approached, and we've trained them not to get into any discussions with these people, only to take their phone details and pass them onto the authorities," said Rajah.
"In the past they were innocent questions. It was just "what is the team tomorrow?" In the past we would easily say, "Joe Soap is not playing. No longer, now we don't announce whether the team is picked or not.
"That is the protocol. If a player is approached, he has to let us know immediately. We have a system. Police are trained to look out for people in the foyers of hotels, who don't necessarily belong there, but look suspicious."
South Africa cricket has been embroiled in match-fixing in the past.
Former captain Hansie Cronje admitted to taking money from bookmakers in 2000.
Cronje was subsequently banned for life before he died in a plane crash in 2002.
Current South African batsman Herschelle Gibbs, who admitted to accepting an offer to underperform on India tour of 2000, was also interrogated by Indian police when he toured with the squad for last year's Champions Trophy in India.
Raja said his players are more cautious in dealing with strangers.
"There's a lot more awareness now than there was five years ago. The players are aware that there are people out there who are interested in finding out things we know, and the players are more cautious.
"Sometimes we took things for granted in the past, we never thought that these things would happen."