Was playing a tournament last weekend (2-man best ball, super fun!). On a par 5 I pulled my drive a few yards and it kicked left off a knob in the fairway and ended up just left of the fairway and just a few inches right of a concrete drainage ditch. I get a drop cause the ditch interfered with my stance, and luckily the nearest point of relief was away from the ditch back into the fairway. So I drop and it rolls a bit back towards the ditch but not all the way back, and standing over the ball I'm pretty sure the ditch won't interfere with my stance anymore, so I accept it as my drop, pick up my tees marking where the ball was and my one club length from there. I'd been planning on going for the green with my 3i, but I notice as I start to set up for my shot that the winds a little stronger in my face than I thought and I might be risking not clearing the front trap. So I change out for my 2h.
Now standing over the ball with my 2h, my right foot is largely in the drainage ditch. I'd probably misestimated where it would have been even with my 3i, and with the 2h now it's definitely interfering with my stance again. At this point the tourney's moving slow and I'd taken all the time to do the whole by the book drop routine with the tees and laying a club down, and it's not a really horrible stance this way (originally I would have had a much more precarious stance). So I just drop my back foot an inch or two to be flat on the concrete and proceed to hit a perfect shot right at the flag about 20' short. 2-putted for birdie.
Here's my question. I took a drop for stance interference from an immovable obstruction. I know if the ball rolls to where I haven't gotten relief, I can drop again and then place if it fails again. But is it illegal to accept the drop when in the end I didn't get the relief that motivated the drop in the first place? Should I have been penalized for just hitting the shot with my foot still in the drainage ditch?