Wisdom needed here!
My lovely 4 year-old Inbred,which looks like this:

has got some rust at the end of the gussets on the top tube and down tube.
This is what it looks like after I've sanded it and treated it with Q-rust.
Down tube:

Top tube:

Should I be worried about the rust I can't see underneath the gussets or is it likely to be just superficial stuff with no significant implications for structural integrity? I'd love an excuse to get a new one but I can't bring myself to replace a perfectly good frame.

