Over the last 18 months I have changed loads of tyres without pinching the inner tube. The last 3 times I have pinched the inner tube twice this afternoon :(. Should have gone to the shared knowledge day :)
Mate, happend to me 18 months ago - all was fine then one afternoon a tyre change resulted in a trip to A&E (don't ask) and then followed a year of trips to bike shop to have tryes fitted as I just lost it completely
An attempt at fitting a front a few months back went well, so changed both on the lads bike and just put a new rear on mine - it will come back mate, but its like climbing back on when you badger it - don't let it get to you!!!!