Quote from atticus:
The strip (vol across strikes) doesn't work that way. The 35s drop or rise is relation to all. In fact, the deep OTM strikes are skewed (higher than ATM); a distinct "smile" driven by the demand (buying) of OTM lottery tickets and the natural writing of ATMs by the buy-side to convert to buy-writes. All vols dropped, but since you're 2x in the 35 the effect is magnified as the wings are less sensitive to changes in vola, put simply. Yes, you're not short excess contracts, but the vega in the 35 is greater than the sum of the wings (vega).
I didn't get any off, but the fly is up a quarter with the stock at 29 and change.
I am long the 20/30/40 fly in October here at 3.90-95 risk (3.80 mid). I'll update when I cover but it's not a journal position.
Edit: Spreads just blew out and it can be bought at 3.50. Adding, and I suggest it's nearly a fwd vol lock here at 3.50. I am averaged at 3.68 on the buys.