I replaced the FPR on my M42 and I remember the new unit's o-ring was very stiff and it took some patience + lube to get it seated in there properly. If you are able to bolt it in it should be fine. It doesn't hurt to be safe but i wouldn't be worrying about a fire. Aside from applying a flame directly to fuel, or having a stream flowing on the headers while redlining, the gas won't ignite. And unlike in the movies your gas tank won't explode should the fuel in it catch fire for some reason.
For the record, my car has a 1 second fuel prime when the key hits position two.