Sneaky partner

Ok so my husband has recently started talking to this lady from work. They text throughout the day and even call each other to check on each other based on his call

Log and texts. I had been reading their conversations, at first she would text him GM, and would text him throughout the day and even text him what she’s making for dinner. Then he started sending her GM texts and would be the one initiating conversation with her and I saw he had even texted her, checking on her while he was with me after work. Long story short I had been monitoring their messages and to me it seemed like whatever but then knowing my partner I started feeling like he was being flirtatious with her. Then all of a sudden I went in his phone to check it and saw he scrubbed all their texts, after coming back from work. I’m now starting to think there’s something fishy going on. Should I be worried or am I paranoid? My feelings are if he had nothing to hide he wouldn’t have erased the texts.