Should I be worry he will cheat?

So I going through my husbands contact to find his mothers new phone i had lose and saw he had a female co worker number saved. What making me ask if i should be worry is I've met this girl one time talk was well and he told me how he met her and how to conversation started by him saying hey and her saying he was married and not interest thoght that was a bit weird. Then they started talking because they could talk about marriage stuff. So around Thanksgiving he came home with her number wrote down on a paper and told me she invited us over her house but I told him no & throw it in the trash because we already had plans at that time the number wasn't saved in his phone. But now he has it again which i know he has gotten it with in the past few days. why would he take her nunber again after I told him not to? Should I be concerned? What should I do?
10 mo
Sorry guys I'm freaking out in my head while typing this but to clarify she said she was married and not interested. I ask him why would she out right say something like that if you said hey he told me that she was getting hit on a lot by other men and thought he was doing the same which I found weird but let it go.
He has also change his appearance around that time to which makes him look younger and he always wants me clothes and shoes. Which is also weird because I never had a problem with it.
Should I be worry he will cheat?
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