Suspicious husband

Hi ladies. 
I know I am going to get a lot of flak for this, but I went through my husbands phone last night. 
He has been acting weird lately. Very angry, short tempered, and mean. The other day he even accused me of seeing someone at work! This isn't like him.... This isn't like us! We are a very drama free couple and rarely get jealous like this. It came out of no where. So it got me a little worried that he might be hiding something which is why I went through his phone. 
I didn't find anything CRAZY. But I did notice that he deleted ALL of his texts messages in his phone this Sunday. The only visible texts were from Monday on.  
I then saw texts between him and a female coworker that I have never heard of before. The text started ubruptly like they were in the middle of a conversation and it was recently deleted. They were talking work, flirting a little, but then she asked him to call her after work. His call history showed he called her and spoke to her for 15min. 
Should I be worried?? This is odd.