I found my husband's dirty underwear in the trash. Is this a sign of cheating?

My husband had been out of town for about a week and when he came back, he was texting some girl. (She does not live in the same state as we do.) He told me that nothing happened, but now this has gotten me suspicious finding his underwear in the trash. He also keeps photos on his phone that she had sent him. Should I be concerned that he's cheating?
I found my husband's dirty underwear in the trash. Is this a sign of cheating?
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