I have had this happen prior times, and the most recent time it pissed me off severely. It also prompted me to take apart my stand and sell all the components (you can search in the for sale sides to find mine, it is still active.)
First - I originally had 2 propane tanks, so I kept 1 full and used the other so it couldn't happen again. Then I sold the grill and the extra tank, and while not paying attention, something happened and the tank went too fast or I wasn't paying attention, and I still ran out. The second time it happened, it prompting the sell off.
Secondly - I have had it happen doing 2 different brew types. On an IPA I would say you are going to be lacking some of the characteristic you were hoping for. You won't have the IBUs from the long boil times, and the aroma won't be there, and will be only gained from the dry hopped. You also will not have had a complete boil-off, so you will be running a little low on your OG. I would still Dry Hop to compensate for the lacking aroma and possibly add some of the hoppyness you missed out on, but probably not a full amount, else it will overpower the IBUs that came up short.
Your flavor profile will probably be a little closer to "Burnout Session IPA" instead of "Burnout IPA", but it should still be an acceptable beer, and may even turn into a standard process.