Nothing really out of the ordinary and especially if you're running an Apple installed SSD. The software they include to look after their installed SSDs may just not have got around to doing all its maintenance.
The included OS X version of DU will do the proper thing with its report and repair, but I'd keep an eye on the SSD and run DU again in a few weeks and check. But don't be too surprised if you see some block count errors. As our home builder would say: shi* happens and not to worry.
DW provides the option to create a brand new directory that DU doesn't do, so you have that option.
But I sure wouldn't run both DU and DW together and at the same time.
Otherwise I'd carry on as you have been doing and don't worry about it too much. Both utilities are just doing their job, and the results you got are pretty typical.
Just make sure you're using the proper version of DW for your OS X version being used, and I'd trust what they say regarding SSD repairs and is well tested and true.
I have the identical SSD in my 2011 MBP and have had for two years now, although back then it was over $800. I routinely use Disk Utility and OnyX on the drive when required without any ill effects whatsoever.