Is it wrong for my girlfriend to give her number out to coworkers who are male?

My girlfriend has given her number out to almost all her female coworkers, and most still work there. Along with this, she has given her number two males who were about to quit and wanted to keep in contact with her. One male, however, texted and to summarize, he was checking up on someone, he claimed he didn't know he was texting my girlfriend. She said she didn't remember who it was (after he said his name), then he said he worked with her, and she gave him her phone number after she gave him a ride. It then went on to her claiming she didn't, and he said maybe he was confused, but as far as I know, my girlfriend and I live in a very small town, so it's very hard to confuse people. She also has a unique name and wouldn't be very easy to mix up with anyone. Then he stated he didn't know how he got her number then, and she claims the same. She also told me that this specific male coworker said, "He's said he's had problems with the boyfriends of the girls he hangs out with," which to me sounds like a red flag. Should I be concerned (which I am), or am I just overthinking things? It doesn't make much sense to me, but I left it alone as I had no proof to anything happening
Is it wrong for my girlfriend to give her number out to coworkers who are male?
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