People have different perspectives on this, but I think as long as there is some acknowledgement and thanks, that's ok. I've tended to put a comment after theirs saying thank-you.
And, of course (as I can see you've been doing
) paying it forward by critiquing other works keeps the site lively. It's a weird thing that a lot of the active critters are not very active writers, so there is not always a work to "crit back", IYSWIM, but if everybody who receives crits gives crits, then there is a lot more critting available.
G