Do you think a crush is cheating?

I got suspicious when my husband started talking about this woman Sandy all the time. Saying things like she's a real firecracker. Sandy is friends with Patsy who works for my husband. Sandy would stop and vist Patsy at work all the time. We have a Graduation Party for my son. Patsy is invite. The day of the party Patsy call my husband. I ask him whats up. He tell me that Patsy wants to bring her son to the party. I'm fine with that. But when Patsy arrives she has Sandy with her too. During the Party I'm watching Sandy. She is looking around for my husband. She spots him turning flipping her hair to look at him. He is also looking at her. Then he sees me he guilty looks at away. but He was not sure if i scene them. Because I had dark sunglasses on. My problem with this is: the phone call earlier that day he was told Sandy was coming. Why not tell me if nothing is going on. Also, He jokes to someone that he see Sandy more then he see's his wife. I confront him that I think she and he have a crush going on. He denies this. What do you think?