A 30A fast-blow should pop open if the circuit needs 30A+ -- not melt it down. Even if the circuit runs at some marginal amount, the fuse should be designed to either pop or handle the load. We've all blown fuses before without a melt-down.

I still think it was a bad contact in the holder. We'll find out soon because I replaced it with another brand of fast-blow 30A fuse and another brand holder. If it melts again (and I'll be checking) it'll be a surprise.