Best guess? The Wooten strings are probably smoother and softer on the fingers than the Blue Steels, and when you switched back they roughed you up a bit. I found Blue Steels really rough when I tried them after using DR Lo-Riders for several years.
I've had a nice double-layer blister on my index for the last 2 weeks. Get 'em every time I put it down for awhile, then start gearing up for a rash of shows or a recording. It's not so bad once you play off the top layer and expose the next blister underneath it.
