Dar- he did suggest that the condition is too lean. Going from level flight at idle to a 90 degree nose up attitude while giving throttle will test the tuning of an engine. You should be able to tune this out like Jim said. I use the 30 second method too, and never rely on the pinch test.

However smoothly an engine will run, I would probably have just a bit more throttle applied before pulling up into a hover. Just to be on the safe side. And, I would apply it very smoothly as I pulled up.