Softest Cotton Bathmat

It's not unusual for me to knit with cotton in the summer heat. No one wants dishcloths anymore, so I wound up knitting this bathmat. It wasn't a difficult knit, but I'm glad I didn't have to undo any of it because the "eyelash" bits obscured everything else.

Pattern: Softest Cotton Washcloth + Bath Mat, by Purl Soho
Yarn: Purl Soho Witch Hazel in 'Classic Denim'
Needle: US8 (started with DPNs, switched to 16" circs, then 24" circs, finished with 60" circs)
Modifications: None except to use a suspended bind off, which was a bit too loose and left the edges a bit ruffle-y.

I'm not sure why I picked blue, since it was destined for a bathroom that's mostly green. I purchased an extra ball, but did not use as much as the pattern said, so now I have 2 extra balls, enough to knit some washcloths as well, which will also be the wrong color for that bathroom.

The bathmat *is* very soft. My only concern is there is no non-slip backing on it. Not sure how I would remedy that. Suggestions?