Yeah, it was never said on-screen that Gary hooked Kirk up with a blonde lab technician named Carol Marcus, but lots of fans over the years have made the connection between the two due to Carol's hair color and the fact that she and Kirk were romantically involved around the same time the future captain and Mitchell were ganging up for their shenanigans and exploits.
I've assumed for a long, long time that the blonde lab technician was Carol, but for the record no episode or film ever explicitly stated it.