In theory, any information about a computer is helpful in attacks. What you did was disclosed recon information or partial user enumeration.
But practically? If the username is not your real name, or doesn't contain any personally identifiable information such as birth date city or anything of the sort and is purely a pseudonym? No don't worry about it.
Targeted attacks on personal computers require more information than just a user name, a lot more, and usually the goal would be some sort of reverse shell that will either be within the permissions of a limited user (your account name) or root, depending on the exploit. In the case the shell results in a user, the attacker already knows your account name. In the case of root, he doesn't care.
And blanket attacks are only effective if they don't rely on enumerables such as usernames so again they don't care.
I think you're fine.
Personally I would blur out any information that distinguishes my computer from any other, but I'm the paranoid sort. I would advise you to be conscious of this sort of thing in the future, but I wouldn't lose any sleep over this one.