I saw this happen too before, but not really a substantial gain like that. I think for me, at the beginning I overworked the cock and bit and as such, the erection level wasn't doing so great. So I took a week off, and afterwards, I was bigger. I think that basically, the jelqing improved the vascularity in the area. However, because it was overworked, it couldn't reach full erection potenial. After the stoppage, it was able to heal up nicely, and with the new circulation, I was able to show bigger.
Now, I haven't seen this happen since, as I think I was merely taking things too fast at the beginning. But yeah, sometimes you think by doing something one way, it will have a certain effect. Often times though, you end up seeing the opposite.
- d_s