Why is guy being jerk when he gave me number?

A couple weeks ago this new guy was hired to work on third shift with my best friend but has to go through training first on second with me until next Friday. Everyone thinks we would be perfect together so last Friday I started talking to him. While talking he seemed really cool with the idea of hanging and when I asked for his number he had no problem giving it to me. I then told him I was gonna call it to save it on my phone and by doing so he would also have mine. My best friend thought he was totally into the idea and since he rather text then talk she said that I should text him to start talking to him since she thinks hes is to shy to approach me. So Monday we said hi but didn't really have time to talk so i took my friends advice and texted him that night to break the ice. All I asked was how he liked the job so far and he texted back "Stop texting me please". My friend wants to know what his problem is since he talks to her but didn't have a chance. My friend by the way is married with two kids and he knows this so he can't be interested in her. Why is he being a jerk all of a sudden?