We can argue definitions if one wishes. Ending up in the ER after a crash and returning home with a cast or splint is "Major" It could have been worse, and thankfully it wasn't (we hope).
It still is worth analyzing what happened so hopefully it can be prevented next time.
SLOW DOWN? Consider rider position & bike balance?
There have been quite a few suggestions of things to consider. Hopefully the OP has had a chance to look at a few things, although, if the bike was disassembled for transport or something, then some valuable data may be lost. Photos at the scene?
The bike is nearly brand new, so there is the temptation to lay the blame on the shop. But, there is also a mix of shop vs rider responsibility. A loose rear wheel could potentially be blamed on the shop, unless the OP removed and re-installed it after purchasing the bike.
BTW: Quick Releases are being used properly, right? Turn it with the QR open until finger tight, then flip the lever to lock (using about as tight as one can get it). Adjust the nut until flipping the lever gets it quite tight.