We have a mailing list, where people can post interesting problems to work on. Less than 2 weeks ago my boss posted a very interesting problem. To accomplish it one needs to read a very mathematically dense research paper, digest the material and then implement the algorithms and test them. I have started working on it as soon as I received the email. My colleague replied to the mail the next day saying that he wants to work on it and my boss didn't say anything, so I didn't report to my boss even though I made significant progress for the last 2 weeks (There is no time limit, its an open problem). Yesterday, I have replied to the thread mentioning the advances I made and the problems I faced. My boss came to me and we had a long chat on how to take this further. My colleague although he didn't work on it for 2 weeks expressed unhappiness after my boss left, that I have worked on the problem in-spite of his mail.
Was what I did professional ?