Indeed I would! After all, one of the SRBs suffered a partial containment failure. The SRB was mostly intact when it was recovered, but you'd be justfied to say that it exploded.
(Oh yeah, so did that big-ass Liquid Fuel Tank, and the orbiter, but that was later).
Yeah, explosion is when parts blow outwards. For rockets and jet turbines, it's a problem. When bits of titanium that are spinning at 20k RPM bust out of their containing nacelle, bad things can happen. Look at the hole: it's pointing away, but when it went, there was a 1 in 4 chance that it would be going somewhere sporting.