It Made Him Sentimental

Purple eyes. One of the primary K'rllian traits. Most intelligent species didn't have purple eyes. Kreznik would know. He had traveled all over the territory covered by the Intergalactic Alliance and had never seen another that did. 

His eyes were a different shade of purple than Lavender's but he had seen it before. His mother and little sister had eyes just like hers. How had he not noticed after being here so long?!

It must have been the glasses. And the fact that when she was in his face like this, her eyes were usually closed or they were in the dark so it was harder to see. 

Kreznik had never thought he would get to see purple eyes again. He was still reeling when Lavender kissed him. Even more overcome with emotion than he had been earlier, he kissed her back with more enthusiasm than usual.