I think I posted something similar when I put a dent in my old 1976 Gibson Grabber - it already had it's fair share of bumps and lumps, but I'd been of the mind to try and not add to them!
Then, as now, people did point out that these things happen. They're regrettable when they do, but this is what happens when you use your basses. Certainly, it's a very painful feeling, but it's one you just have to live with; as, unless you're sealing the bass away to get out and look at from time to time, this is what will invariably happen to even the most cautious of us.
You could try some clear nail varnish to seal the lump, but beyond that I wouldn't panic. You could get it fixed, but you'd likely pay out of all proportion to the damage - and not add any more value to the instrument.
It is annoying, though, I can totally empathise.