Somebody has just mentioned a problem. Could be about the political situation, the weather forecast for the picnic, the freckle that might be melanoma, the poor grammar in a business report. Anything! You have the same opinion or worries, and you want to say this in reply. So, "Yes, I was a bit concerned about it myself!" If the problem is very much in the present, say, "I am a bit concerned about it myself." It means, I am also a little worried. Example dialogue: "You went to Ecuador for your holiday, didn't you?" "Yes, I did. And there was an earthquake!" "That's why I'm asking. I was a bit concerned about your safety." "Ha! I was a bit concerned about it myself! Actually, VERY concerned! But here I am! Alive!"

我想你的理解是对的，毕竟事态是过去式。

If you want to use 'concerned about' for your own skills, you need to express this e.g. 'I was concerned that my writing skills weren't good enough for the job.' 'To be concerned about something yourself' means somebody else is concerned and you too e.g. 'My friend expressed her concern about the situation in Korea, and I was a bit concerned about it myself.'

If a person is concerned about something, he or she is worried about it and it troubles him or her a lot.