Munster replacement hooker Diarmuid Barron accused Mahashe of spitting in his mouth as the pair grappled on the ground in the 17-14 win for the home side, something the latter categorically denied.
Oddly, Barron seemed to need attention from medical staff over the incident, slowing the game while his captain Craig Casey ran to referee Andrea Piardi to report the incident.
Piardi referred it to the Television Match Official (TMO), who could find no evidence. And neither could the citing commissioner.
“The video evidence is inconclusive and there is no clear and obvious spitting action by 6 Lions (Mahashe). The audio statement by 16 Munster (Barron) is clear and he states that 6 Lions spat into his mouth but the audio statement from 6 Lions contradicts this,” the citing commissioner said in a statement.
“He states that he had trouble with his gum shield after the upright contact before the ruck. He categorically denied the accusation.”
It is not the first time an Irish side has made an accusation against South African opponents without clear video evidence, though last time it resulted in a nine-game ban for Bulls hooker Jan-Hendrik Wessels.
It was alleged her grabbed the genitals of Connacht’s Josh Murphy in the Bulls' United Rugby Championship win earlier this season.
The disciplinary committee admitted they had gone on the word of Murphy alone without clear evidence.
It is a case of double-standards that has become all too prevalent with the URC in recent seasons.
The Lions travel to Leinster on May 30 for their URC quarter-final.