Technically, the 1st IR kiss was between Lucille Ball and Desi Arnaz (1951), then Shatner and France Nuyen (1958), with Shatner and Nichelle Nicols another 4 down the road
Saavik. First played by a relatively unknown Kirstie Alley in ST2. Paramount neglected to include a sequel clause in the contract and her agent wanted too much while Paramount low-balled the offer. So they cast Robin Curtis in the role for ST3, and without much to do they left her behind on Vulcan in ST4 while the TOS crew went back to earth (a deleted scene said she was pregnant with Spock's baby when she helped with his pon farr in the previous movie). Saavik would never be conanically seen again, but Robin Curtis would appear in the 2-part TNG episode Gambit. Saavik was considered to be the traitor Vulcan in ST6 but they could never write it in a convincing way, so they rewrote it to a new character Valeris.
That doesbt seem like drama as much as someone with a sense of humor.
Looks like shes just acting "scandalous" during a "professional" group shot. Dude is tossing bunny ears on Shatner at the same time. Koenig is doing kissy face off to the left too.